A Guide to Polyiso Roofing Insulation

Transcription

1 A Guide to Polyiso Roofing Insulation

2 Table of Contents Section 1: A quick guide to Polyiso roofing insulation Section 2: Eliminate Flat Roof Ponding Water with Tapered Insulation Section 3: 5 Tips for Installing Polyiso Commercial Roofing Insulation Section 4: How much does roofing insulation cost?

3 A quick guide to Polyiso roofing insulation 1. What is polyiso roofing insulation? Polyisocyanurate or Polyiso is a ridged insulation board made of closed cell foam. It is usually manufactured in either 4 x 4 or 4 x 8 boards and comes in a range of thicknesses from 1 up to 4. Polyiso is a common commercial roofing product, used under roofing membranes to insulate the building or structure but it can also be use on walls. 2. Are there different types roof insulation? Polyiso comes in flat stock and tapered panels. Flat panels are typically installed on low slope roofs that slant towards a guttering system. Tapered polyiso panels are made with slope or an angle and are used to direct water to a drain or to keep water from standing in corners or flat roofs. 3. Why is this material used? Because Polyiso board insulation works, payback studies can clearly demonstrate positive ROI from reduced energy cost to structures when it is installed correctly and at proper thicknesses. And because polyiso has the highest R-value inch for inch of any other building insulation product available meaning it takes less of it to reach the desired R-value which also mean cost savings. 4. How much does polyiso it cost? The price will be driven by the type and thickness of polyiso you purchase but should average between.35 cents to.42 cents per sq. ft. per inch. To find out how much you are being charged per sq. ft. per inch simply take the price per board and divide it by the amount of sq. ft. in the board. Example One, 4 x 8 piece of polyiso 1 thick cost $ There are 32 sq. ft. in one piece of polyiso because the board is 4 x 8. Take the price per board ($13.10) amount of sq. ft per board (32 sq. ft.) = or.41 cents per sq. ft. per inch.

4 Hint: The price per Sq. Ft. you pay should decrease a little as you move up in thickness. For exact prices on flat and tapered polyiso stock consult with your roofing contractor or roofing supply yard. 5. How much Polyiso do you need? That will largely depend on whether your roofing project is new construction or a re-roof of an existing building. Consult with your local building inspector for specific R - Values required for new construction projects in your area. For re-roof, finding out the amount of insulation the building already has and if it can be saved is a good place to start. From there you can make a decision on how much additional polyiso to add. You can use a climate map get a recommended amount Polyiso insulation but always consult with your local building codes before starting your roofing project. Zone 1 R-15 R-15 R-20 R-20 R-20 R-22.2 Zone 2 R-15 R-20 R-25 R-25 R-20 R-22.2 Zone 3 R-15 R-20 R-25 R-25 R-20 R-22.2 Zone 4 R-15 R-20 R-25 R-30 R-25 R-27.8 Zones 5 & 4 Marine R-15 R-20 R-25 R-30 R-25 R-27.8 Zone 6 R-15 R-20 R-30 R-30 R-30 R-33.3 Zones 7 & 8 R-15/ R-20 R-20 R-35 R-35 R-35 R-38.9

5 Eliminate Flat Roof Ponding Water with Tapered Insulation Using Tapered roof insulation is an efficient way to eliminate ponding water on a flat roof. It can be cut, fit, and installed in a way the moves ponding water towards existing drains, scuppers, or gutters. But for all the great things tapered roof insulation is, cheap is not one of them. Adding a tapered insulation package will substantially increase the price of a flat roofing project. Understanding what tapered roof insulation is, how it works, and the basics of installation will help you make the most of your flat roofing investment. What is Tapered Roofing Insulation? Tapered polyisocyanurate roof insulation or tapered iso for short, is made from the same ridge foam material that normal polyiso roof insulation is made from. Regular iso board comes in flat sheets and in several different thicknesses. Tapered iso is not flat but is made with slope or fall and also comes in several different thicknesses but with slope. The slope causes water to move downhill on what would be an otherwise is a flat roof surface. How it works Tapered polyiso is sold in 4 x 4 pieces or panels that change thicknesses over 4 distance. The amount of the change in thickness in each panel is a 1/4 per foot. This means that for every foot of distance the iso get 1/4 thicker. For example an X panel begins at 1/2 thickness and increases a 1/4 in thickness every foot. Since the piece of iso is 4 long, the thickness increase will be equal to 1/4 times 4 or a rise of 1 over the 4 distance ( 1/2 to 1 /12 )Flat roofers can then arrange the sloped insulation to move water towards roof drains, scuppers, or gutters. X, Y, and Z Panels There are three main pieces of a tapered roof insulation package that are designed to work in conduction with one another. The names of the panels are after the last three letters of the alphabet X, Y, and Z. The size of the insulation is as at the following:

6 X panel measures 1/2 to 1 1/2 in thickness Z Panel measure 2 1/2 to 3 1/2 in thickness Y Panel measure 1 1/2 to 2 1/2 in thickness These three pieces of roof insulation can be installed back to back to for form a continuous slope that begins at 1/2 and ends twelve feet later at 3 1/2. If the slope needs to be longer than three panels or 12 you can continue this same pattern but you will have to add a base layer of 3 flat regular iso behind the Z panel. Remember the Z panel finished height was 3 1/2 so when you add a 3 base behind the 1/2 of the next X panel continues the slope. You can repeat this processes as needed to reach the height or distance you need to remove the ponding water from your flat roof.

7 5 Tips for Installing Polyiso Commercial Roofing Insulation Tip 1. Ordering,Waste factor,and the right kind of board Before you can install any polyiso board you have to figure out what you need and order it. You can go about this two ways: 1.Take the entire Sq. Ft. of the roof deck where iso is to be installed, divide by the Sq. Ft. of the board, usually 4 x 8 or 32 Sq. Ft. then round to the nearest board and add a waste factor ( 10%) and order. Example Roof Deck 126 x 139 = 17,514 Sq. Ft. 32 (Sq. Ft. in one 4 x 8 sheet ) = or 548 sheets to cover the roof deck add 10% waste and your new total is 603 pc 2.You can do a lay out of exactly how the board will fit on the roof deck then count them up and add waste. This method takes more time but will be slightly more accurate especially on smaller jobs. Now you know how much polyiso you need per layer but you still need to figure out what kind of iso your going to buy. If roofing membrane you are using is adhered you're going to need an iso board with a fiberglass facer. If your membrane is going down mechanically attached (screwed down) you don t need this facer. Don t pay for things you don t need, commercial roofing projects are expensive enough. Hint: Watch out for deficit freight charges and fuel surcharges. Deficit freight can apply when your order doesn't fill up an entire semi-truck load regardless of how many truck loads you are buying of iso. You should definitely add these charges to any cost comparison you do between venders. If your job involves a

8 tapered ISO package you may want to consider letting your vendor make a shop drawing and do a take off for you. You won t learn how to do tapered layout in a blog and making mistakes on with tapered ISO can be expensive. Tip 2. Determine the R-value you want and divide the thickness by 2 The NRCA ( National Roofing Contractors Association) recommends that polyiso be installed in two layers with staggered joints. That means that the edges of the first and edges of the second layer shouldn't be directly on top of each other but at least 6 apart. This will prevent a phenomena call thermal bridging where a roofing membrane will condensate on the bottom or warm side of the building instead of the top side of membrane. This condensation can cause a kind of fake roof leak that is impossible to find, it s much easier to stagger the polyiso board. Hint: If the polyiso is going down mechanically attached ( with screws and plates ), you can loose lay the first layer in place (without putting screws and plates in it). Then lay the second layer and screw and plate it down. The screws and plates from the second layer will hold the first. Make sure that your screws are going at least an inch into the deck. Tip 3. Screwed down or Glued down If you are required to adhere you polyiso board consider using one of the many foam adhesive kits on the market. These kits typically consists of two disposable canisters, one of low rise

9 foam and one of adhesive. A hose and gun assembly mix the two materials together as they come out of the gun tip to form beads or lines of adhesive to lay the iso in. The installation is clean and fast. So fast in fact that per every kit you have a man spraying you will need two more men carrying and laying in ISO. If your Polyiso is going down mechanically attached, ditch the cordless drills or impacts and invest in corded screw guns. They will take a little getting used to but will double or triple your production, especially on larger jobs. There are many types and models on the market but the Dewalt 268 has proved itself on our crews time and time again. Each screw gun you purchase will pay for itself through labor savings in a day or two and you won t have to charge batteries all the time. Tip 4. Measure Twice, cut once When you begin to cut in polyiso at the perimeter of the building or around roof details such as HVAC curb and plumbing stacks, take a tight measurement and then deduct a 1/4 of an inch. This will allow you an 1/8 on each side which is well within NRCA guideline of not having gaps larger than one quarter of an inch in size between pieces. Polyiso is difficult to trim up with any amount of precision so trying to cut in ISO too tight the first time can actually make you leave bigger gaps than if you had taken 1/4 of the original measurement. Not to mention the time it takes to cut each board twice. Hint: Use a utility knife to cut, score, and break thin iso but for thicker pieces use a ISO knife or skill saw to make cuts faster and cleaner. Tip 5. Storage and Keep polyiso dry Polyiso is one of the best, most efficient way to insulate a building. That being said the stuff still int cheap. Wet iso will warp and will become much more difficult to install. It will require you to install many more screws and plates to get

10 ISO to lay down or you may even have to discard wet iso if it is to be adhered. Keep roofing insulation will keep your crew moving, make your job look better, and mean that you could return extra pieces to supply house. Hint: Cut the plastic wrapping on a bunk of iso in a way that you can re-wrap it at the end of the day, especially if you aren t going to install every piece in the bunk. You can stretch the original plastic around the remaining iso and hold it in place by pinning it down with some roofing screws.

11 How much does roof insulation cost? Roof Insulation is a very important part of the overall function of a flat roof system and is one of the 4 major costs of a flat roofing project. Here is price guide for multiple thickness of Polyiso roofing insulation in Tips on how to use this price guide: 1. Use only as a guide, check your local roofing supply house for exact pricing on roof insulation 2. You can figure 1 of roof insulation = an R value of 6 or R-6 3. Check your local building codes for R value requirements in your area 4. Two layers of roof insulation with staggered joints is preferable to one thick layer for example use two layer of 2 instead of one layer of 4 in your flat roof assemble 5. Don t forget to add between 5% - 10% waste to your project Depending on the size and shape 6. Estimate the tapered roof insulation by the piece instead of by the Sq. ft. for more accurate take offs. Pricing Guide Continued on next page.

12 INSULATION PRICE / COVERAGE SHEET ITEM COST w/o TAX UNIT QUANTITY PRICE PER SqFt Flat Stock 1" ISO x8 Sheet 32 SqFt $0.39 Flat Stock 1 1/2" ISO x8 Sheet 32 SqFt $0.47 Flat Stock 2" ISO x8 Sheet 32 SqFt $0.62 Flat Stock 2 1/2 ISO x8 Sheet 32 SqFt $0.78 Flat Stock 3" ISO x8 Sheet 32 SqFt $0.93 Flat Stock 3 1/2 ISO x8 Sheet 32 SqFt $1.09 Flat Stock 4" ISO x8 Sheet 32 SqFt $1.25 Flat Stock 4 1/2 ISO x8 Sheet 32 SqFt $1.40 Tapered ISO X $ x4 Sheet 16 SqFt $0.69 Tapered ISO Y $ x4 Sheet 16 SqFt $1.01 Tapered ISO Z $ x4 Sheet 16 SqFt $1.52