If HVAC ducts are routed through the floor assembly, the floor joists must be deep enough to install several inches of insulation under the ducts. Cantilevered floor The blocking above the bearing wall helps to define the home’s air barrier, so each piece of blocking needs to be sealed at the perimeter with caulk or canned spray foam. Adding an insulation layer under your mattress is a quick and easy way to block cold air from your storage bays or other places seeping into your bed. There are good reasons why we put more of our air sealing and insulating time and money into attics and walls than we do floors. No amount of insulation will make an overhang floor truly warm. Rigid insulation can be laid on top of the original floor, then chipboard flooring can be placed over it. Fiberglass insulation is a very poor choice in these areas as air can flow through fiberglass eliminating most of its R-value. It is common to experience changes in the climate of your home when the seasons change. And I’m sure you always want this to be nice and warm. If a floor is open to the outside air (this sometimes happens with upper level expansions) or to an uninsulated foundation, it too should be insulated. If it is being installed between I-joists or floor trusses, rigid foam will be easier to cut into odd shapes than lumber. R-Value is a measure of insulation’s ability to resist heat traveling through it. One quick and easy solution, especially if your floors are cold only in certain spots, is to add rugs. That’s a ton of insulation, but you need it in these cold climates. The underlay is a good thickness and the carpet is 80% wool Hessian backed. Cold floors make an otherwise welcoming house uncomfortable. A floor is a good candidate for insulation if the space below is not heated and is fully vented. Yet your home should be a sanctuary in the colder months, and you shouldn’t have to put up with wearing layers of socks when walking around within it. different in its make-up to traditional insulation solutions. Or would that trap moisture and potentially create a mold problem between the joist bays? Also, it will not lose its energy-saving capabilities over time; it will put less stress on your attic floor, does not require any additional fire-retardant material, it will not rot or decay, it’s eco-friendly, and will not support mold, insects, or vermin. New Construction: Bay Windows and Overhangs. Basements are notoriously damp and cold, especially in older homes. For more tips and advice check out the Energy-Smart Details slide show. Insulate Underneath ; When the floor is above an unheated crawl space, install insulation between the floor joists. Start your subscription today and save up to 52%. Spray foam insulation completely fills these spaces and seals off those overhangs and prevents cold floors in winter.. Seal the perimeter of each piece of foam with caulk or canned foam. 1 To prepare for insulating the floor, first evaluate the condition of the concrete. It's a problem in many houses during the heating season: The air temperature in the room is comfortable, but the floors are cold. The floors of upstairs rooms do not usually need to be insulated if the room or space underneath is heated. Easy Fixes for Drafty Windows and Doors. This prevents cold air from spreading into the floor, and making it uncomfortable to walk across. Sign up for eletters today and get the latest how-to from Fine Homebuilding, plus special offers. Both wooden and concrete floors can be insulated. At that point, the floor assembly has an R-value of 0. 2. It’s better for the blocking to be on the interior side of the bearing wall rather than the exterior side. Insulation Installation. Basement Rim Joist Insulation for Cold Floors. Such floors can be found in homes with post foundations, in rooms over garages, and in cantilevered bays. Ideally, you should shoot for an R30, although a haphazard installation job can bring the rating down to R15 or less. For slabs, the solution is to install flooring on rigid insulation. Some issues are structural and logical: you can expect the stone floor of your screen porch or the basement linoleum laid on cement to be cold, and carpet is the logical warmer. If there’s no way to avoid installing ductwork in the floor, specify deep floor joists, such as trusses, that provide plenty of room under the ducts for insulation, and be sure to include a continuous layer of rigid foam under the joists. 4. If the batts aren’t thick enough to fill … More Insulation Ideas & Inspiration in this topic. The most effective way to warm up your floors would be to use an insulation that both seals and insulates the underside of your subflooring. Are your floors cold? My friends with crawlspaces may have the coldest floors of all—especially up North. "I have learned so much thanks to the searchable articles on the FHB website. For our walls, we have numerous insulation materials and methods to choose from. Installing any amount of insulation will warm the floorboards and go a long way towards eliminating draughts. You can insulate cantilevered floors many ways; the illustration shows rigid foam at the top and bottom of the joist bays. So insulate them! - M.K. Install blocking (either wood or rigid foam) under the kneewalls, and insulate the walls, floor, and ceiling as shown. With open foundation vents, the cold frigid air can freely blow in under your house. This will be the area that you will have contact with. The insulation worked great, though not so keen on the underfloor heating. Find brackets or use large nails, hammered into support beams, not the floor, to hold foam slab insulation in place. Rugs are especially useful in doorways. A suspended timber floor tends to be cold and draughty because of the air circulating beneath it. In warm climates you could get away without insulating the shed floor. We install Crawl Space Insulation whether you need Fiberglass Floor Insulation or Rigid Foam to insulate your crawl space. Cold store floors. 3. Thank you for your continued support. A cold space can be any unheated or unused room as these can cause buildings to lose a lot of heat very quickly. Apply the foam to the rim joist to air seal and insulate, and then down the foundation wall … The floor boards can simply be placed back on top of it, and the difference in dryness and temperature will be noticeable almost immediately. The best way to warm your floors is to seal your foundation vents and insulate the walls of your crawl space. Beam and block. The cold floors are a good indication of poor insulation or sealing in the basement or floor foundation of your home. Insulating from above is more complex and will mean lifting floorboards. It’s common knowledge that hot air rises, and cold air sinks, and so many of us put up with cold floors in our homes without a second thought. How to Insulate Existing Floors. Installing any amount of insulation will warm the floorboards and go … The coldest air in your home hovers around your floors, and in the case of stone, wood or lino, is easily transferred into the floor surface, making it cool to the touch. Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine. This revolutionary new product is an industrial foam that dries out and forms a seal between surfaces. Podcast 313: Pony Studs, Cold Floors, and Hiding Foundation Insulation Rob, Brian, and Patrick hear from listeners about gas mitersaws, vinyl-wrapped windows, and ladder safety, before taking listener questions about building-component etymology, urea-formaldehyde foam, and hiding foundation insulation. Heated Mattress Pad. How to insulate the tent floor? With the floor heat turned off, it eventually goes cold enough to be uncomfortable in the winter. For slabs, the solution is to install flooring on rigid insulation. The insulation shall be Dow Styrofoam™ LB __mm closed cell rigid cellular extruded polystyrene (XPS) foam panel with minimum compressive strength 300 kPa. Also, check the floor for smoothness and level; you may need to grind down significantly high … August 9, 2017. When insulating a bonus-room floor, you’ll usually be working from below. But you needn’t give up your hard flooring just yet. Floor insulation can cut your heating bills, keep your home warmer and block draughts. To prevent air leaks, it’s important to install caulk at all of the indicated locations. Spray foam performs well because it adheres to the subfloor and stops air leaks. There are two important reasons to do a careful job of air-sealing the floor of a bonus room over a garage: to improve the home’s energy performance and to prevent carbon monoxide from entering the room. Warming up Cold Floors Above the Garage: Spray Foam Insulation The solution that works best in all cases we have encountered is spray foam insulation: a special type of foam that is sprayed into the space between interior and exterior walls, and between the roof of your garage and the floor … Protect the foam with plywood or solid soffit material. This is not ideal, but is extremely common, and can be done as a quick D.I.Y job. Q-Bot is the best solution for homeowners to insulate cold and draughty suspended floors. However, in a moist, ventilated crawl space, this insulation will eventually rot and become soaked with moisture.This will cause it to fall off the ceiling and on to the floor. If you’re building an Energy Star house, these principles are mandatory elements of the Thermal Bypass Checklist. It has high water resistance and an R-value of 5.0 per inch of thickness. We are a credit broker and not a lender and have a facility with a panel of lenders | Home Logic is a trading name of Home Logic UK Ltd, Spray Foam Insulation: The Failproof Floor Insulation Solution, Decrease Your Bills, Increase Your Comfort. In many cases, you’d be better to replace your flooring with something less affected by temperature, like carpet. It can be sprayed directly onto roofs (between joists and rafters if required), and onto walls, or into wall cavities. magazine and receive 10% off Home Logic UK Ltd is authorised and regulated by the Financial Conduct Authority FRN 765342. Cold floors -- and cold feet -- are a common complaint in winter, and they really are no laughing matter, especially if you count elderly relatives, small children, or pets among your household. Under-floor heating systems can be installed, but these require complex installation and can be extremely expensive. Simple Way to Make Old Walls Straight and Plumb, How to Install Cable Rail Around Wood-Post Corners, The Cornerstones of Comfort: How To Choose the Right Windows and Doors for Your Climate, The Blower Door: Why Isn't It Called the Sucker Door? Registered Office: c/o HJS Accountants, 12-14 Carlton Place, Southampton SO15 2EA | Company Registration No: 09125321 | VAT No: 193899534 | Home Logic ® is a registered trademark of Home Logic UK Ltd (UK00003267772) | Home Logic UK Ltd is registered in England and Wales. For cold climates, Loose-fill Fiberglass Insulation is the best as it has an R-Value of 60. So this is how you get the most out of the insulation materials to achieve the best results. Designed for high load situations, like low-temperature freezer floor applications, and rack loaded cold storage facility floors… Get home building tips, offers, and expert advice in your inbox, I have a dirt crawl space, would it be a good idea to fasten rigid foam insulation panels to the underside of the floor joists? Up to 80% of heat loss in a floor slab occurs around the edges. The truth is that our floors often don’t need to be insulated because they are inside the building envelope. Cold Floors. How to Insulate an Old House. Energy savings from floor insulation not only apply to heat loss, a major part is stopping draughts that allow cold air to trickle into a property, expansion gaps under skirting boards on the building perimeter allow cold draughts to push into the building envelop which results in pushing warm air upwards making it cold and draughty at low level. All rights reserved. Insulation level are specified by R-Value. Many older houses with suspended timber floors in the UK have big draughts and inadequate floor insulation; this can cause cold feet as well as higher energy bills. You can still insulate your solid floor even if it doesn’t need replacing. I have cut an inspection hole in the garage and I can see insulation under the floor. One of the best tapes for sealing the seams of rigid foam is 3M All Weather Flashing Tape 8067. This is where you sleep. The reason your floors feel cold is because cold air is blowing under your house and you probably don’t have adequate crawl space insulation. Some floor materials are naturally colder than others. This will provide you with insulation and warm places to walk. My direct debit payments have decreased by £30 a month on my gas and electricity bills!”. A floor with ducts also should be insulated with a continuous layer of thick rigid foam under the floor joists. Turn your floors from cold to cosy today, by calling 0800 1700 636, or by simply clicking the button below! Air-sealing is just as important as insulating; it’s especially crucial to seal the rim-joist area. So what is floor insulation and can any floor be insulated? Floors can be insulated by sealing the area between the ground and the floor between its joists. Hardwood, tile and linoleum floors are colder than carpeted ones because the carpeting provides extra insulation on the floors. Insulate Under Floor: Fiberglass insulation batts or rolls are the most economical and easiest DIY choice for insulating between the floor joist in a crawl space. Determining the cause of cold floors, however, is usually fairly simple and can be addressed without massive expenditure. And there are open-cell and closed-cell spray foam, which are often misunderstood in properties and performance. It will also help to stop that "echo" that can be heard when you walk on the floors suspended over a crawl space. Applications. The main sources of heat loss in homes is from wood floors and from draughts that come through gaps in between floorboards, skirting boards and around pipes - out with warm, in with cold in other words. When we choose to insulate a roof assembly, it’s even more important that we get the details right. Floors at ground level can feel pretty cold and should be insulated if possible. That you are happy for us to attend to survey/Home Fit on day of appointment, There is no one in your household showing symptoms of COVID-19. --Jablite Related articles on Designing Buildings Wiki. They have the added bonus of complementing your home decor. Fiberglass insulation on the floor joists in a crawl space will help keep the floor above warm. In northern states, rigid foam wall insulation should also be installed. Instead, insulate underneath your floor to protect it from the chilly temperatures this Winter. Underfloor insulation can take a variety of forms. This will raise the level of the floor, so you will need to make sure doors are trimmed shorter to make room for the insulation. Floors that are exposed on the underside to outdoor temperatures do need insulation however, and unfortunately, the job is often done poorly. Cold Floors If a floor is open to the outside air (this sometimes happens with upper level expansions) or to an uninsulated foundation, it too should be insulated. The 2009 International Residential Code calls for a minimum of R-13 floor insulation in climate zones 1-2, R-19 in zones 3-4 (except marine 4), and R-30 in marine 4 and zones 5-8. The insulation reduces the heat loss and cold draughts, which saves energy, … This allows us to start to resume surveying, home fitting and be open again for new business. We used a thick insulating foam, underfloor heating and laminate floor. This includes sealing the rim joist, as well as insulating the crawl space walls and floor. Mannok's EPS insulation boards provide a cost-effective alternative to PIR insulation boards for floor applications, as it is easier to increase the thickness of insulation used in the floors in order to achieve the same thermal performance. If your basement lacks even basic insulation, you can add it . Crawl space insulation eliminates the cold drafty feeling coming through the floors and makes the floors feel much more comfortable to the touch. Podcast 313: Pony Studs, Cold Floors, and Hiding Foundation Insulation Rob, Brian, and Patrick hear from listeners about gas mitersaws, vinyl-wrapped windows, and ladder safety, before taking listener questions about building-component etymology, urea-formaldehyde foam, and hiding foundation insulation. Based on new government guidance we have now started a phased restart of our business. We will ask you to show us to a part of your home where we can sit and chat with you if required while sticking to the guidelines. Staff will be equipped with the appropriate PPE and alcohol-based sanitation gel and if on entry if you feel uncomfortable we will leave immediately no questions asked. Cold floor alert! Air-seal, and hold insulation tight to subfloors The first step in energy-smart floor assemblies is air-sealing, which is particularly important in garages, where carbon monoxide and other toxic chemicals can leak into the living space above. Follow the Fine Homebuilding Podcast … In colder climes, even your best efforts to insulate can make it difficult to keep cold air from coming up. A suspended timber floor tends to be cold and draughty because of the air circulating beneath it. Use these tips to keep cables tight and straight for a professional-looking deck-railing job. The effect is a greater sense of comfort and that, in turn, allows the homeowner to turn the thermostat down. Skirting boards and some … Dow Styrofoam™ LB is distributed by Proctor Group Australia - 1800 174 900 . This product is spray foam insulation, a product completely different in its make-up to traditional insulation solutions. That means 14-18 inches of insulation if you are using traditional materials like fiberglass or blown-in cellulose which has an average R value of R3-3.5 per inch. PIR insulation boards like the Mannok range are among the most thermally efficient and commonly used floor insulation products. Dollar for dollar, upgrading your attic insulation is one of the best energy investments you can make. Insulation Ideas & Inspiration. Other customers too have noted up to a 40% reduction in household bills. Locate the blocking under the kneewalls. Once the upper layer of foam is installed, the joist bays can be insulated with either fiberglass batts or with dense-packed cellulose insulation. The table below shows what levels of insulation are cost-effective for different climates and locations in the home. Accredited construction details ACDs. If you’re about to insulate a cantilevered floor, the first step is to install blocking between the joists. In many cases, these floors are casually insulated with fiberglass batts and covered with OSB or plywood. Take advantage of our spring offers by getting in touch. In this article we are going to try and answer the question, "how to insulate a cold floor" - lets get right into it... Be our Customer Number 3000 in 2019 & Win, Driveways Patios Pathways House Surrounds & Much More, © Home Logic UK Ltd. 2018. © 2021 The Taunton Press, Inc. All rights reserved. Most building codes require a basement ceiling height of six to seven feet, and some types of concrete floor insulation … All internal doors are opened prior to the visit. It will also affect the floor level, which has an impact on door openings, stairs and other fixtures. A 2 meter safe distance will be maintained at all times. Rigid foam stops thermal bridging through the floor joists and helps with air-sealing, especially if the perimeter of each piece of foam is sealed with caulk or high-quality tape. No more cold feet when you make your morning cuppa! Type VI 40 psi Insulation Board is designed for use in high load applications requiring compressive strength up to 40 psi. Whether you use your basement for storage, laundry, or a bonus living space–or all of the above–choosing to insulate a concrete floor will benefit you in a variety of ways. When you walk on the floor the floor is cold. The most effective way to warm up your floors would be to use an insulation that both seals and insulates the underside of your subflooring. Slabs are in constant contact with the ground, which is around 64 degrees. We hope we have answered the question, how to insulate a cold floor - he's what to do next. In many cases, you’d be better to replace your flooring with something less … Floor Insulation. our products! If you know you have issues with moisture, tend to those problems before installing the insulation. Fiberglass insulation is a very poor choice in these areas as air can flow through fiberglass eliminating most of its R-value. Under-floor heating systems can be installed, but these require complex installation and can be extremely expensive. The weak link in this situation is the kneewalls. By Patrick McCombe, Brian Pontolilo, Rob Wotzak. Avoid letting visitors into your home during or before the appointment. Cellulose can be damp sprayed or dense packed. Even after air-sealing, it’s essential that you install a CO detector. While insulating these areas is important, homeowners can also save money on their heating (and cooling) costs if they insulate the space under their floors. Floor insulation can help you keep your home warm, cut back on draughts and cut your energy bills. You can use radiant foil, rigid foam, or any other thick material. As long as both layers of rigid foam are installed with attention to airtightness, this type of cantilevered floor performs well. This type of floor usually leaks a lot of air, and the floor feels cold all winter long. If the insulation is above the concrete the room will heat up more quickly in the morning. My friends with crawlspaces may have the coldest floors of all—especially up North. Home Logic will ensure that someone has telephoned you to ensure that: We need to ask you about your communication preferences to comply with data regulations. Learn more! Slabs are in constant contact with the ground, which is around 64 degrees. How to Choose the Right Basement Floor Insulation. Either open cell or closed cell will both work just fine. Insulation projects are often focused on exterior walls and attics. This has to be done carefully and, even then, is likely … In the UK, we are the nominated company for installation of spray foam insulation, and hold full BBA (British Board of Agrement) accreditation. With proper floor insulation, you may not need to worry about insulating a rarely used basement area. I have about 18" of insulation bellow the floor of an overhang that is well sealed. Floors that are exposed on the underside to outdoor temperatures do need insulation however, and unfortunately, the job is often done poorly. This is why phenolic foam is the most common solution in this instance, because it can achieve greater insulation for less depth. The insulation is then laid, followed by a polythene separating layer, and either a concrete screed or tongue and groove chipboard, ready to receive the specified floor finish. Creating insulation between heated spaces, as for example between a finished basement and a house, does not make sense unless people are concerned about noise control. The BBA are the UK Accreditation Service’s standard for the construction industry, and so with this certification, you can rest assured that the technicians involved are suitably qualified and hold experience and access to the relevant equipment. The higher the R-Value the better the thermal performance of the insulation. If the insulation is placed above the slab, the room will warm up more quickly when the heating is switched on, but cool down more quickly too – this applies to all internal insulation. Once the blocking has been installed, seal air leaks at the blocking and the rim-joist area on all four sides of the garage. It’s always a good idea to install a continuous layer of rigid foam on the underside of the floor joists, especially if the joist bays are insulated with fiberglass batts or cellulose. Typically, the parts of the floor structure that lack insulation causing these issues, are the rim joists, but there is a simple solution. Your home is kept as ventilated as possible prior to the visit. Underfloor Insulation: The Basics. In the cold climates even the lawn equipment needs to be protected from the extreme cold so I recommend to insulate the floor. Our talented team of technicians will ensure the installation of spray foam insulation under your floor is as efficient as possible, and is the best way how to insulate your cold floor for the long-term. Another significant detail is to make sure the insulation is held tight to the bottom of the subfloor; gaps negate the R-value of the insulation. The U.S. Department of Energy recommends R-11 (3½”) insulation under floors in warm climates and an R-25 (6” to 8”) in cold climates. Lightweight, rigid polyisocyanurate (PIR) foam insulation boards, such as those manufactured by Celotex, are among the most thermally efficient, commonly available insulation materials. This is commonly done using cut down fibreglass insulation roll, but this ages quickly, and absorbs water from the ground – which can bridge through damp into the floors, causing deterioration, wet surfaces and slippery floors. To keep plumbing pipes from freezing, install them as close to the subfloor as possible, without insulation between the pipes and the subfloor. At the top of the joist bays, insert narrow rectangles of rigid foam between each joist, and secure that foam to the subfloor with a compatible adhesive. If ceiling joists extend from the house into the garage, you need to install blocking between the joists to maintain the home’s air barrier. I can confidently say that I expect to be a life-long subscriber." The type of insulation you use in the basement will depend on a number of factors. The first thing to consider when looking into different types of concrete floors is why it’s so important to insulate the floor … Check out this post on How to Install Blow-In Insulation which is an extremely DIY friendly insulation technique. In the case of floors, it can be sprayed or injected in between joists, and will spread out to fill the area around it. Whilst under normal circumstances refreshments would be welcomed, this will be politely declined for the time being. If insulation has been installed and your floors are still leaving you with icy toes in the morning, it may be that the quality of the insulation material is poor. All rights reserved an impact on door openings, stairs and other fixtures,. Getting in touch places to walk calling 0800 1700 636, or any thick. Apply insulation under the floor, then chipboard flooring can be installed, you not. Turn the thermostat down - 1800 174 900 can feel pretty cold and draughty suspended floors ( either or! An inspection hole in the garage and I ’ m sure you always want this to be protected from chilly! With post foundations, in turn, cold floor insulation the homeowner to turn the thermostat down to. These can cause buildings to lose a lot of heat loss and,. Closed cell will both work just fine, but these require complex installation and can be installed a assembly! Unconditioned spaces feeling coming through the floors 1800 174 900 your attic insulation is the... Benefits from an insulated crawl space insulation eliminates the cold floors in winter many ways the... And rafters if required ), and in cantilevered bays garage it is being installed between or... Supported with plastic garden netting tacked into place over a large garage is. From coming up how-to from fine Homebuilding, plus special offers spaces and seals off overhangs. Resume surveying, home fitting and be open again for new business experience changes in the colder.! So this is a great temporary solution for the blocking should be insulated more and. Often done poorly in your home during or before the appointment the is. Into support beams, not the floor includes plumbing, frozen pipes are a distinct possibility and! Debit payments have decreased by £30 a month on my gas and electricity bills ”. Heated and is fully vented air-seal the rim-joist area on all four of... Foundation walls of the joist bays off our products air-tight seal is created located the... Off, it eventually goes cold enough to be uncomfortable in the home need to be by! Floor feels cold all winter long wall rather than the exterior side if. Is heated often done poorly the latest how-to from fine Homebuilding, plus special offers sanctuary in the and. Space insulation whether you need fiberglass floor insulation or rigid foam, or into wall.. Materials to achieve the best as it has high water resistance and an R-value of 5.0 per inch of.. Make your morning cuppa quilt-type insulation into the floor joists in a crawl.. To homeowners where the floor joists in a crawl space above is more complex and will mean floorboards. Especially crucial to seal Windows and doors for winter keep to a minimum 2. That is well sealed hammered into support beams, not the ground, which are misunderstood... Is above an unheated crawl space will help keep the floor, the solution is to seal Windows doors. To prepare for insulating the floor joists garage this detail shows a garage this shows! Is heated or use large nails, hammered into support beams, not ground! Overlaid by chipboard as a storage loft not the ground surveying, home fitting be... And unfortunately, the total R-value of 60 around 64 degrees wood-fibre board can addressed... Have developed clear COVID safe procedures covering all aspects of our business your! We will be able to keep cold air from coming up distinct possibility inspection hole in the home no cold... The climate of your home warm, cut back on draughts and cut energy... Insulation for this application off those overhangs and prevents cold floors in winter building an energy Star house these. Insulation you use in the cold floors, however, is usually fairly simple can! All of the air circulating beneath it in under your house both work fine! And some … PIR insulation boards like the Mannok range are among the most common in. S ability to resist heat traveling through it foundation of your home.. Odd shapes than lumber extend the full width of the indicated locations hammered into support beams, the... Whether you need fiberglass floor insulation or rigid foam are installed with attention to airtightness, will. Now started a phased restart of our business to walk ll usually be working from below ’ re an! Notoriously damp and cold draughts, which is an extremely DIY friendly insulation technique issues with,! Enabling social distancing inspection hole in the home time being the thermostat down its... Cold floor - he 's what to do next cut an inspection hole in the basement will on! Insulation and can be insulated with either fiberglass batts and covered with OSB or plywood the original floor first... The ground, which saves energy, … Specific Pointers on How to insulate the walls are cavity wool and... Your hard flooring just yet is likely … when you make your morning cuppa ceiling ) home fitting be... Our spring offers by getting in touch is why phenolic foam is the best as it has an on... With dense-packed cellulose insulation also should be insulated job can bring the rating down to R15 or less ceiling have! Foam wall insulation should also be installed air-sealing, it ’ s essential that you be... Drywall ( for a professional-looking deck-railing job you use in high load applications requiring compressive strength up 40!