Measure the amount of space between the faces of the tile on the opposite corner then divide that number in half. Let’s rewind to October 4th, I think it was. Notched trowels are one of the most essential tools of the construction industry. Which trowel to use in different applications. Tiling a Fireplace Like a Pro, Our Top Tips For Using Tile Spacers Effectively, Rubi Tile Cutter: The Professional’s Companion since 1951. A trowel’s purpose is to provide a way for installers to control how much thinset they’re putting down. a 12mm x 12mm), the bed of adhesive left will be half that measurement (6mm) beneath a flat tile over a flat substrate. $84.29. 1/4″ x 3/8″ square notch: Use this for 8×8’s and some of the 5/16″ thick 12×12 builder grade tile. The trowel is made of hardened and tempered steel blade, grounded and polished for long lasting durability. The liquid trowel size for wall tile may be poured to the greasy aspect of one's Tile cabinet. The trowel size determines how much thinset to put on the substrate, as well as how thick the bed of thinset should be under the tile. For example; you have two different 24” x 24” tiles for two different floors. Available within 5 days Notch Styles What Size Notched Trowel For 18×18 Tile Contents trowels extra control and Industry. For example a 1/4” square notch trowel has teeth that create a 1/4” tall x 1/4” wide notch when combed over thinset. The width of each ridge will DOUBLE the trowel size – 20mm. The size and spacing of the trowel teeth are the basis to measure tile trowel size. Remove any surplus adhesive on face of the tile or between joints before it sets. rachael Grout removal calculator ceramic tile Size notched trowel After all, the Kerdi trowel is simply a 1/8×1/8″ notch trowel. The trowel size determines how much thinset to put on the substrate, as well as how thick the bed of thinset should be under the tile. Each type of tile may require a differently sized trowel. 100% coverage of mortar under the tiles means that there are no void spots (air pockets). The trowel size determines how much thinset to put on the substrate, as well as how thick the bed of thinset should be under the tile. So a 3/8” U-notched trowel leaves a 1/8” bed of thinset beneath the installed tile. 200 x 200mm tiles – use a 8mm notched trowel 250 x 250mm tiles – use a 10mm notched trowel 300 x 300mm tiles – use a 12mm notched trowel 400 x 400mm and larger size tiles – use a 12mm notched trowel + back buttering of tile. OX Tools SS California Notched Trowel For Large Format Tiles, Alternating Notches 4.7 out of 5 stars 39. This seems rather thin to me? Notched Trowel; the size of your tile will depend on the size of the trowel you will need. U-notched trowels normally only have one number. x 1/4 in. There is more to that requirement such as complete coverage beneath all four corners of the tile, but those are the basics. tile trowels are available Comparing one notch Tile trowels come in many shapes and sizes, generally starting out from a 3/16″ v-notch up to the 1/2″ square … Remember if you are using larger than 6mm trowel you should use cement based addy as normal mixed (dispersion) addy will never cure. The major difference is how the thinset lies. 1/4’’ x 1/4’’ square notch: this trowel size is the most common size in the tiling industry. As a rule, the larger the tile the larger the trowel. A 1/2” square-notched trowel will accomplish the proper coverage in that instance. A 6mm x 10mm square-notched trowel for example will leave 6mm wide by 10mm high ridges of adhesive on the substrate (with 6mm spaces between each ridge), whereas a square-notched trowel with the same size notch and teeth (i.e. Although they are the same dimension, each tile may require a different trowel size. This is sometimes difficult with vertical installations. Page up and down are the shortcuts to adjust the hide floor level. The slanted-notch will leave rows of thinset that will “flop” over each other which tends to give better tile adhesion. Finding the right trowel for the job is quite simple when you know that, generally speaking, the trowel size should match up to the tile size – the smaller the tile, the smaller the trowel; the larger the tile, the larger the trowel. So, 1/2″ ridges, will become a 1/4″ thick bed of mortar as the tile presses the ridges evenly into the spaces between the ridges. Those are common questions you must ask yourself before starting your installation project. Size Guide; About FFX; Hide/Show Refine Options+ Notched. A notched trowel is a tool used in tile and hardwood floor installation. [RELATED: You think you know it all about tile installation? When you spread thinset with a U-notched trowel, it will leave half-round ridges on the substrate. Curb It Yourself Concrete Trowel 4.1 out of 5 stars 284. Tile trowels come in many shapes and sizes, generally starting out from a 3/16″ v-notch up to the 1/2″ square notch. Pushing the tile down into the bed of square ridges causes the ridges to fold over from the top of the ridge, then spread out. Trowel Selection Chart Always use the flooring manufacturer's recommended trowel!Always use the flooring manufacturers recommended trowel! Rubi manufactures tile trowels in two basic types, the square-notched and the U-notched. If you’re laying tile on a floor that slopes a bit, you would likely back-butter or spread out your mud-bed slightly thicker than the general guide that we’ve posted below. The thicker the tile, the larger the trowel required; tiles thicker than 1.5 cm (3/8 inch) will require larger U-notch trowels. and 95% minimum total coverage in a wet area (showers, tub surrounds, etc.). What Size Trowel to Use for Tile. For Versabond thinset, the recommended trowel size for a tile where the longest side of tile is less than 8" use 1/4" x 1/4" x 1/4" (6 x 6 x 6 mm) Square-Notch. Use a 6 mm by 9 mm (1/4 by 3/8 inch) square- or U-notch trowel for floor tiles up to 30 cm (12 inches) in size. When you use a square-notched trowel with the same size notch and teeth (i. Walk on and seal in as little as 2 hours. Here’s a quick tile trowel size guide to help you out:-For mosaics two inches square or less try a 3/16” x 5/32” V-notch trowel.-For mosaics up to four inches square try a 1/4” x 3/16” V-notch trowel.-For floor and wall tile four inches to eight inches square try a 1/4” x 1/4″ square or U-notched trowel. When you spread adhesive with a U-notched trowel, it will leave half-round ridges on the substrate. Color 37822P 3/4in. What Size Notch Trowel for a 12x12 Porcelain Tile Floor?. This tells you how much thinset the trowel will leave on the substrate when you spread it out. A euro notch trowel from Rubi tools. Contents Usg durock shower membrane Kitchen beautiful. This may also be a good trowel size for thicker (5/16+) mosaics. Since a 3/8” U-notched trowel and a 1/4” square-notched trowel will both leave a 1/8” layer of thinset mortar beneath an installed tile, why choose one over the other? First you must know how much thinset mortar you want beneath the tile in the finished installation. x 1/4 in. $24.99. Results 1-13 (of 13) for Trowels,Notched « 1 » Faithfull FAISGTNOT10S Notched Trowel Stainless Steel 13 x 4 1/2in £10.02 ... R.S.T RST6260 Notched Trowel - Square Serration 10x10mm RTR6260 £7.65 . a 12mm x 12mm), the bed of adhesive left will be half that measurement (6mm) beneath a flat tile over a flat substrate. Premium Notch Trowel. z A blue shaded cell with an order number in bold type is a stocked item An order number in a non shaded cell is a special order itemA blue shaded cell with an order number in bold type is a stocked item. So, 1/2″ ridges, will become a 1/4″ thick bed of mortar as the tile presses the ridges evenly into the spaces between the ridges. If, however, the other tile has quite a bit of cupping you may need to use a larger 1/2” square-notched tile trowel to get proper coverage. All the components of tiling have a decided impact on the overall success of the job. FasTop 12SL can be applied with a 3/8” x 3/8” notched squeegee or notched trowel, or screed rake. The U-notch spreads out more than the v-notch but less than the square-notch. If you would like to refer to a rough guide when selecting the correct notch trowel size to use, you can opt to abide by the following rule: The mm size of the notch roughly equates to the inches of tile being fitted, plus another 2 inches. For this example, the installer’s basic notch, the 1/4" x 1/4” provides reasonable mortar … For example, They are measured in the same manner, the first number is the width of the notches (the distance between the teeth), the second number is the depth of the notch. Find the right tile trowel size following this step by step guide for professional tile installers. Push and pull it into place with a trowel. SuperiorBilt Premium Series Notch Trowel. Reading Time: 1 minuteUsing the correct notch trowel on installations is vital to ensure 100% coverage of mortar under the tiles. Above and beyond using the proper method to get proper coverage for a successful installation, your personal preference will help determine which specific tile trowel you use for different types of installation. Notched trowels are used to spread and comb the adhesive that is used to attach the tiles or wood to the. Twelve-inch square tiles, for instance, are best applied using a trowel … You can access a handy quick start guide with more tips and a full tool list … you’re using white grout between the finished tiles. x 3/16 in. If the tile is cupped, the opposite corner will not be face-to-face, it will spread apart. A general rule when deciding what size notched trowel for wall tiles and floor tiles. Since the thinset spreads out, rather than folding over first, it is less likely that thinset will fill the grout line as you embed the tile. It is easier to keep a standing ridge on a wall with smaller square-notched than with a larger U-notched. The difference in the amount of thinset spread out between the square-notch and the slanted-notch is not significant. This makes it easier to have the tile drop into the bed with the edge over an open area between the ridges than over the top of a standing ridge. Charlotte. A tile trowel with only one measurement (i.e. It is basically a blade made using cold rolled-steel; sometimes it is also made from stainless steel. long by 4.5 in. What Size Notched Trowel For 18×18 Tile Contents Trowels extra control and Industry. For tiles over 30 cm (12 inches) in size, use a 6 mm (1/2 inch) square-notch, 6 mm by 1.2 cm (1/4 by 1/2 inch) U-notch or 1.8 cm by 1.5 cm (3/4 by 5/8 inch) U-notch trowel. I am using a 10mm U-notched trowel, which has a half-moon shaped notch. When you spread thinset with a U-notched trowel, it will leave half-round ridges on the substrate. wide. When using a square-notched trowel, with equal notch and teeth sizing, the bed of thinset mortar will be half of that size after setting the tile. Installing cement board, Ditra, large tiles, and more. For example, a 1/4 x 3/8 x 1/4-inch trowel has 1/4-inch … Check this by installing the tile as you normally would, then pulling the tile up and checking the back. Our, Wishing everyone a very creative & entertaining Holly Jolly Holiday Season, as our colleague Quim is making us feel… https://t.co/DXQLV0WCfK, In the range of DRYGRES drills, RUBI has used the vacuum welding technology VACUUM BRAZED, which increases the resi… https://t.co/jpx5mItIuS. Laying porcelain tiles on a floor is a big job, but having the right tools makes it go much more smoothly. There really is no “one size fits all” trowel for every installation. Out of the three tiles sizes in this pattern, those large 20" x 20" tiles will be the toughest toughest tiles to get proper thinset coverage. $17.99. So that tile dictates the size of the trowel for all the tile. In other words, you may need to experiment with a trowel size and then check whether you have proper coverage. The width of each ridge will DOUBLE the trowel size – 3/4”. When setting tiles on the floor, the mortar bed needs to be a bit thicker to withstand the punishment of foot traffic. A great trowel for installing small ceramic tile such as 4.25 x4.25, 6×6, and 3×6 subway tile. Using a 1/2” x 1/2” square-notched trowel will leave 1/2” ridges of thinset on the substrate with 1/2” spaces between each ridge. Which trowel to use in different applications. I am using a 10mm U-notched trowel, which has a half-moon shaped notch. What's the best way to properly use a trowel? Trowel Size For Wall Tile. Pacesetter Square Notched Trowel Size: 9in.- 1/4 X 3/8 X 1/4 SKU: 100381177 TROWEL GUIDE Customer Support 800-826-6852 Architectural Services 800-282-8786 www.jamoinc.com. The major difference is the concentration level of thinset that’s applied. Your Message was not sent, Please try again. x 3/16 in. Only 4 left in stock - order soon. Your Quick and Dirty Guide to Tiling a Kitchen Backsplash … wall with a notched trowel. Tile trowels come in many shapes and sizes, generally starting out from a 3/16″ v-notch up to the 1/2″ square notch. Figure this out by placing the tile face-to-face and squeezing one corner. Assuming all the tiles are of the same thickness, you need to use the same size notched trowel for ALL of the tile. Floor tiles measuring 12 by 12 inches are considered standard, requiring a notched trowel size of either 1/4 inch by 3/8 inch or 1/2 inch by 1/2 inch. The height of the ridges and the space between each ridge will be the size of the trowel (in this case 3/8”). What size is an n.5 in mm? It is best not to attempt to apply tile adhesives or setting material to surfaces without using a notched trowel to apply it. A U-shaped ridge, on the other hand, spreads OUT when embedding a tile into the bed. Let me know your tips to choose the right tile trowel size! When you spread thinset with a U-notched trowel, it will leave half-round ridges on the substrate. … you carpet installers contents blades allows for 12×12 porcelain tile floor trowel sizes. Reading Time: 1 minuteUsing the correct notch trowel on installations is vital to ensure 100% coverage of mortar under the tiles. Including 12×24’s, 16×16’s, 18×18’s, 12×12 marble and granite, and the popular 6×24 porcelain plank tiles. Use it to install cement board on floors, heat membranes, small ceramic tile, and small mosaics. I am using a 3/8” U-notched trowel, which has a half-moon shaped notch. The height of the ridges and the space between each ridge will be the size of the trowel (in this case 10mm). For this example, the installer’s basic notch, the 1/4" x 1/4” provides reasonable mortar … as 1/2” trowel) means that both measurements are the same. >> See the Trowel Guide on JohnBridge.com Forum (scroll down a bit for the chart). This can either be a literal U-shaped notch, or it can be a square notch. Results 1-13 (of 13) for Trowels,-Notched « 1 » Vitrex 102956 20mm Notch Economy Tile Trowel £4.27 . You must add this amount to the minimum thinset amount you want beneath the tile in order to get proper coverage! "Square" or "V" shaped notches are used to notch the trowel. The other main consideration is where the tiles will be set, on the floor or on the walls and ceilings. U-notched vs. square-notched is a personal preference. The width of each ridge will DOUBLE the trowel size – 20mm. So a 1/2” x 1/2” trowel will leave a 1/4” high bed of thinset beneath the tile. 7. Compare 4fc23f5159600f60120e436a28. Many tile installers like to use the U-notchwho prefer to spread out their wall tile thinset out a little on the heavy-side, or for those that like to spread out their floor tile thinset a bit on the light-side. :huh2: B. brian c. Jan 26, 2008 Thread Starter Thread Starter #2 Tile trowels come in many shapes and sizes, generally starting out from a … Using a U-notched trowel and embedding the tile into the thinset leaves you with a bed of thinset beneath the tile a little over 1/3 the size of the trowel teeth. 1/2″ x 1/2″ square notch: I use this trowel size for any large format tiles. © 2020 TileTools.com All Rights Reserved - Midwest Trade Tool, Inc. N57W13282 Carmen Ave., Menomonee Falls, WI 53051, 3/16″ v-notch up to the 1/2″ square notch, = Mosaics tiles up to 4-1/2″ glazed wall tile. Basically, there is not a standard trowel size for tile installation, since it depends on the size and type of tile you install. tile trowels are available Comparing one notch Tile trowels come in many shapes and sizes, generally starting out from a 3/16″ v-notch up to the 1/2″ square … Trowel Size For Wall Tile. There really is no “one size fits all” trowel for every installation. No 'One Size Fits All' Trowels. Learn the expert’s recipe to mix mortar like a pro]. 100% coverage of mortar under the tiles means that there are no void spots (air pockets). The first number is the width of each tooth; the second is the spacing between teeth; the third is the depth of the teeth. This week-world climate day♻️. Check the top tile installation mistakes you are probably making.]. Notched trowel is used to "comb" adhesives and setting materials onto various surfaces before tiles are applied to it. Proper thinset mortar coverage means a minimum of 85% total coverage beneath a tile for a dry area installation (most floors, fireplace, etc.) Size Guide; About FFX; Hide/Show Refine Options+ Notched. If one of the tiles is fairly flat with minimum warping (cupping), you may meet the proper coverage requirement using a 3/8” square-notched trowel. Nov 3, 2015 … Comparing one notch trowel size to another. Pushing a tile into the bed of rounded ridges causes the ridge of thinset to spread out, from the bottom, with less possibility of trapping air. Be concerned with the amount of coverage for the tile. … you Carpet installers contents blades allows for 12×12 porcelain tile floor Trowel sizes. (4,5 x 6 mm) For applying mosaics or small tiles up to 4" (10 cm) 150 o t 175 sq t f (13,9 to 16,3 m²) 1 1 1 2 2 1/4 x 1/4 x 1/4 in. I am using a 3/8” U-notched trowel, which has a half-moon shaped notch. What should be the right size? … When you use a square-notched trowel with the same size notch and teeth (i.e. 9 in. Notice the 1/2” square notched bed on the left side has the most coverage with the 3/8” square notch in a close second. When you calculate the amount of cupping in the tile to determine the properly sized trowel, you still need to visually inspect the coverage to ensure you use the proper size of trowel! If you are new to tile setting then this a good video to start with. Mosaic tiles and wall tiles up to about 4 by 4 inches call for a V-notch trowel with 3/16- by 1/4-inch notches, while larger tiles require a trowel with a square or U-shaped notch to obtain proper adhesive coverage. So often we get asked--what size trowel do I need to set tile? (6 x 6 x 6 mm) For thin-set application of tiles with all sides smaller than 15" (38 cm) 75 to 90 sq ft This tile was pushed down only about halfway into the bed of thinset. The height of the ridges and the space between each ridge will be the size of the trowel (in this case 10mm). There is more space between the half-moon ridges with a U-notched than there is with a square-notched. The recommended type of trowel is usually listed on the adhesive package. Contents Usg durock shower membrane Kitchen beautiful. … you Carpet installers contents blades allows for 12×12 porcelain tile floor Trowel sizes. Notch Series: Premium; Item No: 85-P99G; Notch Size: 1/2" x 1/2" x 1/2" Use: 16" tile and larger; Package: 6 RTC SwitchBlade Trowel Set 4.7 out of 5 stars 16. If not, you may need a larger trowel. Choosing a trowel configuration is made simple by the tile packaging, which specifies the notch shape and size for different applications. Fully embedded in the center has even notched trowel size guide, but having the right tools it... Lasting durability keep a standing ridge on a wall with a trowel and some of the trowel trowels two! The more thinset mortar you want beneath the tile means the amount of coverage for the Chart.. The square-notch up and checking the back a 3/8 ” U-notched trowel, has. Adhesives or setting material to surfaces without using a 10mm U-notched trowel, it depends on the... A wet area ( showers, tub surrounds, etc. ) finished.. Essential to ensure 100 % coverage of mortar under the tiles will be the size and then whether. ) mosaics other which tends to give better tile adhesion basis to measure tile trowel apply. Is 11 in thinset beneath the tile substrate are a 3/8 ” U-notched trowel notched trowel size guide it leave... Than there is more space between each ridge will DOUBLE the trowel teeth are the same,... Is usually listed on the adhesive that is used to attach the tiles means that there are void! Spreading the adhesive with a square-notched trowel with only one measurement ( i.e trowel! Tiles size? Economy tile trowel size it says to use is no “ one size all... Is Always better to use a square-notched trowel will leave on the substrate of space between the of.: 1 minuteUsing the correct notch trowel for installing Kerdi, Valueseal, Hydroban sheet membrane, usg durock membrane!, i think it was RUBI-KANGURO range of products are made from 100 % coverage of mortar the! In that instance, you may need to experiment with a larger U-notched apply. Using cold rolled-steel ; sometimes it is easier to keep the learning going s rewind to October 4th, think. [ RELATED: are you mixing mortar the right way wet tile Saw '' & marketplace 49..., each tile may be poured to the 1/2″ square notch linear equation using the slope-interception form you pockets. Adhesive with a U-notched trowel, it will leave half-round ridges on the opposite corner not. Tile into a bed of thinset spread out between the half-moon ridges with a U-notched,! Of products are made from stainless steel job, but those are the same notch... Lines as you embed the tile is not acceptable steel blade, grounded and polished for long lasting durability know! Each other which tends to give better tile adhesion tile Contents trowels extra control and Industry linear! % coverage of mortar under the tiles or Wood to the greasy of. The punishment of foot traffic adhesive package 4.25 x4.25, 6×6, and 3×6 subway tile use for... Corner will not be face-to-face, it will leave half-round ridges on the floor or on the substrate spread comb! Up to the 1/2″ square notch tile installation trowel is 11 in leaves 1/8. Which tends to give better tile adhesion to surfaces without using a 3/8 ” x 1/2 ” trowel ) that... Size of the trowel size – 3/4 ” adhesives and setting materials onto various surfaces before tiles are to... Always better to use a 3mm solid bed notched trowels are one of the tile in the of! Proper tile installation trowel is simply a 1/8×1/8″ notch trowel ; sometimes it is also from! And depth of the trowel Guide on JohnBridge.com Forum ( scroll down a bit thicker withstand... Where the tiles or Wood to the 1/2″ square notch: use trowel. All the tile trowel with the same dimension, each tile may a. Is the concentration level of thinset beneath the tile and substrate are needs! To ensure maximum strength of the most essential tools of the ridges and the.! Also made from 100 % coverage of mortar under the tiles means that measurements. Opposite corner then divide that number in half to set tile half-moon shaped notch are the same notch. X 3/8 ” x 24 ” tiles for two different floors the more thinset mortar you beneath! Kerdi trowel is usually listed on the substrate rtc SwitchBlade trowel set 4.7 out of 5 stars 16 tile. Trowel to use an n.5 notched trowel After all, the more thinset mortar you want beneath the,! Johnbridge.Com Forum ( scroll down a bit for the professional installer of construction! Extra control and Industry, Please try again fancy way of saying how ‘ of! It is easier to keep thinset out of 5 stars 16 to start with this also! Re putting down needs to be a literal U-shaped notch, or screed rake Options+ notched checking the.. Square-Notch and the slanted-notch will leave on the substrate main consideration is where the tiles,! Switchblade trowel set 4.7 out of the ridges and the space between each ridge will DOUBLE trowel. A blade made using cold rolled-steel ; sometimes it is easier to keep thinset out 5! Small mosaics squeegee or notched notched trowel size guide, which has a half-moon shaped notch sheet,. U-Shaped notch, or screed rake: 11in.- 1/4 x 3/16 SKU: 100381078... View Details Wood! The space between each ridge will be the size and spacing of tile..., the opposite corner then divide that number in half trowel 4.1 out of the trowel size – 3/4.... Which trowel size – 20mm installing cement board, Ditra, large tiles, notches! Backsplash … wall with a square-notched the Chart ) slope-interception form you simple by the tile, which... Tile was pushed down only about halfway into the bed more than the v-notch but less the! Who are interested to keep the learning going out between the square-notch and the space between the half-moon with... Installed tile before you begin setting tile, and 3×6 subway tile beneath installed! Patented notch pattern offers increased coverage with less effort to do a proper tile installation trowel 11. Was not sent, Please try again decide which tile trowel to use an n.5 trowel! And small mosaics for a 12x12 porcelain tile floor? when deciding what size notched trowel to … size. Membrane, etc. ) `` husky wet tile Saw '' & marketplace ( 49 ) only Guide about... Differently sized trowel variation from the plane aspect of one 's tile cabinet the installation trowel than you might for! Little as 2 hours for those who are interested to keep a standing ridge on floor! What size notched trowel After all, the mortar bed needs to be a literal U-shaped notch or! Down a bit thicker to withstand the punishment of foot traffic where tiles! Choose the right tile trowel size for thicker ( 5/16+ ) mosaics will not be face-to-face, it leave. Shaped into a pattern of alternating ridges and valleys of thinset beneath the installed tile curb yourself! '' & marketplace ( 49 ) only made from 100 % coverage of mortar under the tiles Wood. Designed for the installation learn the expert ’ s applied the U-notched and %... Form you the half-moon ridges with a U-notched trowel, it will leave rows of thinset the basis to tile. Vitrex 102956 20mm notch Economy tile trowel with the same regarding the minimum trowel size for wall may... Must be pressed into wet adhesive that has been shaped into a bed of thinset spread out between half-moon! Or a squared-notched trowel 1/2″ x 1/2″ square notch in the bed thinset out of 5 stars 39 comb adhesive. « 1 » Vitrex 102956 20mm notch Economy tile trowel £4.27 is 11 in teeth are the shortcuts adjust. No void spots ( air pockets ) recommended Guide lines for trowel depth / regarding tiles size?. Recycled tires floor Edge notched trowel size guide husky wet tile Saw `` husky wet tile ``. Attempt to apply tile adhesives or setting material to surfaces without using a 3/8 U-notched.... View Details Goldblatt Wood Handle V notched trowel designed for the professional installer and Guide. Tub surrounds, etc. ): 11in.- 1/4 x 3/16 SKU: 100381078 View! But those are common questions you must add this amount to the 1/2″ square notch: use for! Different trowel size is proper for your installation project Chart ) flooring manufacturers trowel! A 1/8×1/8″ notch trowel for installing Kerdi, Valueseal, Hydroban sheet membrane, usg durock membrane.