The Optimum Basement Wall

Transcription

1 The Optimum Basement Wall Solutions to the Wet Blanket Basement Problem February 27 th,

2 Adapting to Change! We ve made significant advances in water management. Customers no longer accept that musty old basement smell. 2

3 Today s New Home Buyer: Expect their basements to be warm, comfortable and dry. Do not accept mildew, mould and other odors. Want to finish their basements on their timeline. Think their basement is leaking when they see vapour on the poly and; Freak out when they see mould. 3

4 Basements Built to the Current OBC: Builders are frustrated as homes built to the current OBC are very susceptible to mould and moisture issues. It is a real challenge to explain this to customers. Building Officials are frustrated because the builder has followed the OBC. But their phone keeps ringing. TARION faces a warranty challenge: How to deal with customer complaints for an item they can t warrant. Builders and Industry Stakeholders are looking for a solution. Builders frequently tell customers to wait before finishing their basement. This often goes against the need for utilizing available space given the cost of housing. 4

5 The Definition of Insanity: Continuing to do something over and over again and expecting a different result! As an industry we know basements are not working. The OBC does not address moisture migration within the concrete wall. Over the years I have ripped open many insulated basement walls and found that the majority of them had mould. So we decided to build a better basement wall. I asked my CBO Leon Bach to work directly with me to ensure that my new wall system would be accepted. This is the story of how we developed the Optimum Basement Wall. 5

6 The 4 Principles of the Optimum Basement Wall! Limit the ability for water to enter the wall. Use of materials that won t trap moisture. Change the location of the Air Barrier. Allow drying paths for moisture migration. 6

7 STEP 1: Limit the ability for water to enter the wall. 7

8 Inward Bound Vapour diffusion. Moisture moves from wet to dry and from warm to cold. During the summer months, moisture in the concrete wall will try to flow from the outside of the concrete wall into your drier, conditioned basement. The 6ml poly traps the vapour which condenses on the surface of the poly as there is no place for the vapour to go. So customers see moisture on the poly... And your (our) phone starts to ring. Our first step was limiting the opportunity for moisture to enter the foundation wall. 8

9 Limit the ability for water to enter the foundation wall. 1. Damp proofing (Tar) applied to exterior of wall. (Limits wicking from surrounding soil). 2. DELTA -MS Membrane applied to exterior of the wall. (Keeps bulk water away from foundation wall). 3. Cold joint between foundation and footing is caulked. (Keeps bulk water from slipping under foundation wall). 4. Footing Drainage. (Big O connects to sump pit system to limit excessive water accumulation under basement floor). 5. DELTA -FOOTING BARRIER is applied to the top of footing. (Limits wicking from wet footing). 1. DAMP PROOF (TAR) 2. DELTA -MS Membrane 3. Cold Joint 4. Footing Drainage 5. DELTA -FOOTING BARRIER 9

10 DELTA -FOOTING BARRIER: Capillary break between the footing and the foundation wall. Significantly reduces wicking from footing into foundation wall. Less wicking = dryer foundation wall. Permeance 0.8 Perms ASTM E96-05, Proc. A Test 10

11 Delta Membrane And Damp Proofing (Tar): Tar provides a capillary break between the footing and the surrounding soil. Significantly reduces wicking into foundation wall. Bulk water is managed away from the foundation by the Delta membrane. NOTE: Tar application behind the Delta Membrane is not required by the Manufacturer. Optimum Basement Wall recommends the tar application as an additional layer of protection against moisture wicking. 11

12 STEP 2: Use of materials that won t trap moisture. 12

13 Outward Bound Vapour Diffusion. During the winter months, humid air in the home is migrating toward the exterior concrete walls where it will cool and condense. If it is cold enough the migrating vapour will freeze on the housewrap and you don t know it until the customer calls about water on their basement floor. We decided to work with ROXUL to develop an insulation product (COMFORTBOARD IS) and the Better Basement Wall System that would not hold on to the migrating vapour and had mould resistant properties. Once we understood the COMFORTBOARD IS properties, we decided to see if we would be able to eliminate the house-wrap against the foundation wall. 13

14 Use of Materials that won t trap moisture. 1. Header wrap is extended over the basement wall top plate. 2. House wrap installed next to the foundation. R6 ROXUL COMFORTBOARD IS installed over the house wrap. 3. Stud wall is built against the COMFORTBOARD IS with a slight gap for straightening of wall. (Note that a PT bottom plate is used). R14 ROXUL COMFORTBATT installed in the stud wall. 4. 6ml Poly Vapour Barrier applied as per OBC. 5. 6ml Poly under bottom plate is lapped over top of the vapour barrier. 6. Compacted Granular Sub Base limits moisture wicking into the concrete basement floor. 1. HEADER WRAP 2. MOISTURE BARRIER / ROXUL COMFORTBOARD IS 3. ROXUL COMFORTBATT 4. 6ml POLY VAPOUR BARRIER 5. 6ml POLY UNDER BOTTOM PLATE 6. COMPACTED GRANULAR SUB BASE 14

15 R6 ROXUL COMFORTBOARD IS installation. Roxul COMFORTBOARD IS NOTE: Installation can be done before the basement slab is poured and before framing. 15

16 Are there concerns with installing ROXUL COMFORTBOARD IS to top of footing? When we used ROXUL on the exterior of the foundation it was often soaked with water. Will the same issue happen on the inside? It should not because it s exposure to water will be very different. 1. ROXUL can be used as a moisture barrier because it won t hold water against the studs. 2. ROXUL will not wick up from the footing. The loose cellular structure of ROXUL COMFORTBOARD IS limits wicking action (unlike concrete which acts like a sponge), so it does not pull water upwards against gravity. In addition we ve designed a relatively Dry wall, with controls to limit inward and outward bound vapour diffusion, so there will be less moisture entering the wall. 16

17 R-20 Basement Solution Next steps: Look at the removal of the house-wrap. Change 6ml Poly to an air barrier as well as vapour barrier. COMFORTBATT 24 O.C. CAN/ULC-S R14 COMFORTBOARD IS R6 CAN/ULC S702 R6 17

18 A problem area is penetrations of the rim joist The headers have a skim coat of foam applied after all mechanical penetrations are completed. This acts as an air sealant and improves the warmth of the inside surface temp. DOW Froth-Pak is code compliant as a sealant. CCMC L R22 ROXUL COMFORTBATT installed in front of foam provides a Classification A fire stop. 18

19 Bodycote Report on Protection of Foam Plastics: ROXUL is an acceptable option (Classification B Rating) COMMENTS AND CONCLUSIONS Dow Chemical Canada Inc. submitted the mineral fibre batt/polyurethane foam plastic system for testing to determine if it would meet the requirements of Clause (1)(c) and Clause (2)(e) of the 1997 Ontario Building Code and Clauses (1)(c) and (2)(e) of the 2005 National Building Code of Canada, Division B. The requirement is that the protective cover/thermal barrier must meet the requirements of Classification B when tested in accordance with CAN4-S124. (OBC harmonized with the National Building Code on these references in the 2012 OBC). The 5.5 inch thick mineral fibre batt insulation identified as Roxul Flexibatt R21.5 (Now rebranded as COMFORTBATT R22), used as a protective covering for the Froth-Pak spray-in-place polyurethane sealant, qualifies for a Classification A rating based on an average temperature rise of less than 140 C and individual temperature rise less than 180 C at the 15 minute mark of the test. The 5.5" thick mineral fibre batt insulation would therefore also meet the requirements of Classifications B, C and D. 19

20 The Trouble with Poly The vapour barrier was not air sealed and did not prevent moisture migrating into the basement wall. PROBLEM: You don t know there is an issue until you have water on the basement floor and the client is calling to complain. We decided to limit the opportunity for moisture to enter the insulated wall. We had already determined to use products that would not hold moisture. The Optimum Basement Wall 20

21 STEP 3: Change the location of the Air Barrier! 21

22 Continuous Air Barrier The Optimum Basement Wall The OBC now requires a Continuous Air Barrier. Many builders are putting a house wrap against the concrete then installing the insulation. The concrete wall and floor are used as the air barrier. 22

23 2013 wall revision from meeting with Dr. John Straube NOTES: House wrap against concrete wall is removed. Air Barrier moves to the warm side of the insulation. COMFORTBOARD IS extends to top of the footing. Poly to be completely air sealed using applicable tape. Acoustical Sealant under the bottom plate, or Acrylic Sealant between slab and bottom plate is critical. 23

24 Header Wrap goes over the front of the insulated wall. Air / Vapour barrier is then installed over top of the insulation. Here s the problem: The vapour barrier is the problem! 24

25 Vapour Barriers and Inward Bound Vapour Diffusion The ROXUL does not hold water against the studs, but the 6ml poly does. There is no place for the vapour to escape. Client thinks their basement is leaking. 25

26 Vapour Barriers and Inward Bound Vapour Diffusion Here you can see the mould on the face of the stud. The customer is not happy because they see the mould. But the builder has done everything correctly, according to the OBC and to the Best Practice Guide for Basements. 26

27 We ve managed our water migration, so where is the water coming from? Summer time humidity and a hot sun cooks the concrete, forcing moisture through the wall where it hits the cooler poly and condenses. The vapour barrier traps water in the insulation and limits the ability for the wall to dry. Excess moisture in the wall will lead to mould. 27

28 STEP 4: Allow drying paths for moisture migration. 28

29 What if we change the function of the Air Barrier? 29

30 The Optimum Basement Wall MemBrain complies with: CCMC s Technical Guide for Vapour Barrier CCMC s Technical Guide for Air Barrier Systems for Exterior Walls of Low-Rise Buildings MemBrain can serve as an alternative solution that will achieve at least the minimum level of performance for vapour barriers and air barrier systems with respect to condensation control required in: NBC 2005, Sentences (1), (2) and (3), and Articles , and Smart MemBrain replaces 6ml poly on the top 1/3 to ½ of the wall: (Easiest if you use half rolls). 30

31 The limitations in the use of MemBrain as the designated vapour barrier: The MemBrain film shall be protected from direct ultraviolet (UV) exposure and covered with interior gypsum wallboard within seven days; Detailing around window should limit the exposure of the MemBrain to sunlight, either by covering it, or using poly in the window sill area. 31

32 Using the Optimum basement wall you can go from this 32

33 To this in less than an hour for a few hundred dollars This is a retrofit of an existing home. 33

34 To this: A wall that dries to the inside during summer time humidity events. 34

35 Detailing around Window Easiest method is to go right over opening. Then use the smart poly to tie back in to the window. Less cost and uses existing materials already being used for the Optimum Basement Wall. Provides a drying path at the window framing. 35

36 OBC Alternative Code Compliance This design has been approved as an Alternative Compliance under the OBC for use in St. Thomas, Central Elgin, Aylmer and Ingersoll. 36

37 Proving it! The Optimum Basement Wall The Optimum Basement Wall is being studied in our Discovery Home for the next year by George Brown College. Our goal is to change the Ontario Building Code to recognize the need to control vapour migration. 37

38 CONCLUSION Following the 4 basic principals of the Optimum Basement Wall, we can construct walls that work. Limit the ability for water to enter the wall. Use of materials that won t trap moisture. Change the location of the Air Barrier. Allow drying paths for moisture migration. 38

39 QUESTIONS? 39