Gaps in house wrap

jdezMarch 7, 2014

When we asked about this, it was explained that exterior materials would cover the OSB on the outside of the house and it shouldn't be a problem. I just wanted to check here and see if anyone thinks this needs to be covered by tape or canned spray foam or just don't bother.

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The OSB (oriented strand board) is sheathing. Housewrap is the paperlike material that some builders apply to the exterior of the sheathing. From this picture, I can't tell if there is housewrap on or not.

No matter what the exterior finish is to be--brick, vinyl, wood siding, cement board etc.--you are required to put something on the exterior of the OSB. That material acts as a drainage plane and sometimes as an air barrier. If you have an interior air barrier, gaps between pieces of OSB are less important.

From the picture you posted it looks like your builder doesn't bother with any kind of window flashing.

As well, the corners while structurally OK, are not energy efficient: there's no place to put in insulation. (See link.)

Here is a link that might be useful: Framing a Corner

This post was edited by worthy on Sat, Mar 8, 14 at 15:52

    Bookmark   March 7, 2014 at 11:42PM
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I caulked every OSB seam/crack. Anything larger than a fine crack was filled with spray foam. Why? Because we wanted a tight house. The insulator also filled window voids, bands.


    Bookmark   March 8, 2014 at 8:06AM
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First of all, the horizontal sheathing joints of a house braced with continuous structural sheathing are required by code to be blocked. There is an exception for seismic zones A & B and for zone C if certain requirements are met but my structural engineer will not use that exception. IMO a good builder would block the joints in order to develop the full lateral wind resistance of the sheathing. Structural sheathing is only as laterally strong the strength of the nails that secure it.

From the photo it appears that some kind of house wrap has been installed over the sheathing and wrapped into the window openings. House wraps, if not well sealed at the joints and the perimeter, are poor air barriers and I suspect that will be the case for this builder so you would be wise to seal the sheathing gaps. I suspect the builder will think this is foolish but from the photo I would say he is either ignorant of good building techniques or likes to save money in the wrong places.

It is difficult to caulk or foam a joint that has nothing behind it so it would be best to apply flashing tape over the gaps. The cheapest easy to find tape is probably 4" Tyvek Flashing Tape (not Tyvek Seam Tape). It should be rolled with a roller tool.

Here is a link that might be useful: Tyvek Flashing Tape

This post was edited by Renovator8 on Sat, Mar 8, 14 at 11:07

    Bookmark   March 8, 2014 at 10:01AM
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Sophie Wheeler

You're dealing with Low Bid Bud. Anything you want (that should be standard good building practice) is gonna be deemed ''too fancy'' or ''extra cost'' to be done. This build is gonna be a full time job for you to come in behind him to do what needs to be done. The window install is particularly concerning. You've got to ramp up your knowledge quickly, and decide if you want to keep on keeping on with this guy when you'll be doing a large part of the work if you want a decent build.

    Bookmark   March 8, 2014 at 10:12AM
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Thank you all for the advice. I will cover the gaps and then I'll plan to work on the windows and doors. It might take me a week or two but I'll get it done. Thanks again.

    Bookmark   March 8, 2014 at 10:44AM
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The windows can only be flashed and panned after they are taken out.

    Bookmark   March 8, 2014 at 3:55PM
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This post was edited by worthy on Sun, Mar 9, 14 at 1:21

    Bookmark   March 8, 2014 at 3:56PM
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I'm curious about what's holding up the huge header above the window.

    Bookmark   March 8, 2014 at 4:10PM
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Renovator8 - I went back thru my pictures and couldn't find a straight on picture of that header but all headers in the house are done the same, so it would be done like the door and window pictured below:

Worthy - I was told that the flashing was done from the outside and the inside gaps will be filled and insulated prior to being covered by trim later. I will keep a close eye on this. It WILL be done right. I paid extra $$ to get some more efficient windows for our Southern cooling climate and I would not be happy if that extra expense was wasted because of a lazy install. Let me know if you think I need to do something NOW.

    Bookmark   March 8, 2014 at 4:50PM
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Headers over openings (doors, windows, etc), should be designed to transfer the load down to the foundation through direct bearing. Said differently, there should be wall studs UNDER the ends of the headers. As installed in your photos, only the nails holding the header to the adjacent stud will transfer the load from above, and nails aren't designed to transfer structural loads. I'd have a long talk with the framer, and if it was my house, it would all be removed and done correctly.

Good luck with your project.

    Bookmark   March 8, 2014 at 7:18PM
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The window and door are framed fine. The big window is not. Nice catch. It could be as simple as adding the missing cripple to transfer load.

Looking at your flashing detail on the outside... Take your builder out in the yard. Dress him in a rain suit with the jacket tucked into the pants. The proceed to hose him down and see if he gets your point.

    Bookmark   March 8, 2014 at 7:58PM
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I can't tell if the flashing on the bottom is below or above the flashing on the left side of the window.
worthy, rollie, is it best to flash the window 'below' the house wrap or on 'top' of it? I watched Tom on TOH flash windows and doors years ago. I had it taped and watched it several times. He showed it in detail. He flashed the windows as they were installed and the house wrap went over that. What's your opinion?
I don't see allot of what people are seeing here. The original post only shows one pic and it is on the inside corner with a partial window showing and one window in the middle that the header is in the wrong place. I see NO house wrap anywhere(except on the one side of window) and that is what the OP was asking about. As mentioned, the window that is shown has the header in the wrong place. Whoever framed that window doesn't have a clue what they are doing. Do you have house inspectors(city, county, personal, if the area doesn't have inspectors you NEED to hire personal) inspecting this house as it's being built?

This post was edited by robin0919 on Sat, Mar 8, 14 at 23:43

    Bookmark   March 8, 2014 at 11:39PM
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I like rollie's suggestion for the window flashing. :) Tuck his pant bottoms into his boots too.

    Bookmark   March 8, 2014 at 11:40PM
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Thank you all for your observations and helpful advice. DH will meet with the builder Monday morning. I am very appreciative.

    Bookmark   March 9, 2014 at 12:08AM
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Sorry don't know how to insert URL from the iPad.

Slideshow: Flashing a Flanged Window with Housewrap and ...
Nov 22, 2012 - Veteran builder Carl Hagstrom demonstrates the right way to install a flanged window unit by detailing the housewrap and flashing tape.

Prevent Window Leaks with Proper Window Installation: The Family ... › Parts of the House › Windows
New or replacement windows can be made completely watertight with just a little extra effort by properly installing the sill pan, house wrap and flashing tape.

    Bookmark   March 9, 2014 at 12:26AM
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Thanks Oaktown

    Bookmark   March 9, 2014 at 12:30AM
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Worthy - I was told that the flashing was done from the outside and the inside gaps will be filled and insulated prior to being covered by trim later.

I see your builder is using Zip brand flashing tape. Perhaps he should check out the manufacturer's detailed video on Youtube demonstrating the correct use of their product as window flashing.

(To be fair, are you sure the jambs, sills and headers are not flashed? Sometimes these threads jump all over the builder based on a misunderstanding of the homeowner or poor communication.)

When housewrap is used, the flashing tape goes over the wrap. It's important to check compatibility; or use tapes and wrap from the same manufacturer. Many tapes require primer over OSB,

Using flexible flashing over housewrap to create a pan flashing. Source: Fine Homebuilding

Here is a link that might be useful: Building Science Corp.: Common Flashing Details

This post was edited by worthy on Sun, Mar 9, 14 at 12:06

    Bookmark   March 9, 2014 at 1:58AM
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There are many ways to install a window. The members here will probably only agree on some general principals. The first choice is how the weather/air barrier is installed (before or after the window) and whether it will wrap into the opening or not. In this case, the builder chose to install a house wrap first and wrap it into the openings so for better or worse that is settled.

The next step would be to install "sill pan flashing". This is optional but it has been the standard for good construction for a century with adhesive applied synthetics taking the place of soldered copper. Some builders believe house wrap serves that purpose but at least the corners should be sealed. I don't see evidence of any sill flashing in the photos but it might be there. Sill pan flashing can be a prefabricated of copper or plastic or built up with self-adhering flashing often called "flashing tape" as shown in worthy's post. Some tape manufacturers recommend a spray primer on wood sheathing or concrete. Some common brands are Dupont Tyvek FlexWrap NF, StraightFlash and Flashing Tape (butyl); Grace Vycor Plus (rubberized asphalt) and Vycor Ultra (butyl); Huber Zip System Tape (butyl).

The Zip System tape appears to be installed here. Huber's installation details assume their tape will be used on their wall panels that have a factory applied acrylic coating in lieu of house wrap so the installation instructions do not apply to the OP's project, however, the only important difference from Tyvek's instructions is no house wrap flap at the head. The Zip System also offers a liquid applied sill pan and panel joint seal that is very interesting.

At any rate, sill pan flashing should lap over the rough sill and turn up the jambs about 6 inches as shown in Worthy's post. The corners require special attention since that's where water wants to go.

Some manufacturers recommend that the rest of the jambs or even the head be wrapped with flashing tape. Apparently DuPont believes the Tyvek house wrap serves that purpose BUT recommends that it be cut horizontally so it covers the entire jamb frame instead of cutting it diagonal from the corners as they recommended in earlier years. (see link below)

When full perimeter opening flashing is applied it makes little sense to wrap house wrap into the opening so I assume it was not done here.

Then the window is installed sometimes with a bead of sealant under the nail fin but that can get very messy. If sealant is used there should be breaks in the bead at the bottom fin for drainage.

After the window is installed the vertical side flanges are taped first and at the window head a horizontal flashing strip is applied under a flap cut in the house wrap to avoid the "pants in the boots" syndrome. The bottom fin is left untaped for the same reason.

There is not much that can be done for the OP's installation but it might be possible to cut a flap in the house wrap above the head and tape the top nail fin to the sheathing (primer might help here). Then make sure the bottom nail fin is not sealed so water can escape. Also use a roller to seal the tape to the house wrap since it appears to be lifting in the photos. If it still won't adhere, rub it with a piece of backer paper until it does.

Since the primary approach of your builder is to wrap house wrap into the openings, I would recommend referring to Tyvek's installation instructions with the warning that DuPont is in business to sell products, not protect your house. There are many flashing materials that can be substituted for Tyvek brand products.

Here is a link that might be useful: The Tyvek way

This post was edited by Renovator8 on Sun, Mar 9, 14 at 9:29

    Bookmark   March 9, 2014 at 9:03AM
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Worthy and Renovator8 - Thanks for the details. I'm going to print it out and show them how we want things to be done. Thanks again.

    Bookmark   March 9, 2014 at 10:03AM
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Be prepared for some pushback as from what I see the windows will need to be taken out for them to be properly flashed.

    Bookmark   March 9, 2014 at 4:01PM
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If the windows are going to be removed, might as well remove the header and provide proper support for it. Previous point about other door and window headers being correctly installed with cripple studs is well taken.

    Bookmark   March 9, 2014 at 6:19PM
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I don't know what the applicable building code is in your jurisdiction but the 2009 IRC says:

"R703.8 Flashing. Approved corrosion-resistant flashing shall be applied shingle-fashion in a manner to prevent entry of water into the wall cavity or penetration of water to the building structural framing components. Self-adhered membranes used as flashing shall comply with AAMA 711. The flashing shall extend to the surface of the exterior wall finish. Approved corrosion-resistant flashings shall be installed at all of the following locations:
1. Exterior window and door openings. Flashing at exterior window and door openings shall extend to the surface of the exterior wall finish or to the water-resistive barrier for subsequent drainage."

Unfortunately, this is not a very useful standard for window flashing so unless the contract required the windows to be installed according to the window and/or weather barrier manufacturer's instructions, you will probably be forced to pay for any changes in the work.

The basic problem that you have stumbled upon is that decades ago home builders readily accepted the new nail-fin plastic and metal clad windows as essentially "self-flashing" (codes actually exempted them from needing flashing) and adopted the strategy put forth by DuPont, etc. that it was appropriate to seal the windows to a loose plastic weather barrier as a backup to the weathering face of the exterior cladding (brick veneer, siding, etc). This seemed to work until it was discovered that the nail-fin windows tended to eventually leak at the corners so the good builders went back to protecting the wood sill and jamb framing (sill pans, etc.).

Of course, this is much more important in wet climates then in dry ones so attempts to develop a national standard to address this issue has so far been unsuccessful.

Discussing these issues with a builder is basically telling someone how to do something that they have been doing for a living for decades so it can be a tough negotiation. This is why the installation instructions for windows should be bound into the construction drawing set or referenced by the contract and attached to it. And it doesn't hurt to staple it to a few of the rough jambs before the windows arrive.

Good luck

Here is a link that might be useful: interesting paper about window flashing

    Bookmark   March 9, 2014 at 7:44PM
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I dont think the original picture showing the unsupported end of the header necessarily needs to have the window removed to transfer load. While its certainly better to have on piece structural members, this can be rectified quite easily by adding the missing cripple. Without seeing the floor plan, it may be that this window is on a non structural wall,(but why dies it have the massive header then) but it looks like its not carrying any roof load..

I agree, there may not be enough information into the window flashing. While the head piece is wrapped into the jamb, they very well couldve cut the head piece loose when they installed the window, and brought it to the surface.. It does appear that way, with the flashing tape shown at the top of the window not as wide as the sides or bottom.. The housewrap doesnt show at the head of the window or door in the second picture..

This post was edited by rollie on Sun, Mar 9, 14 at 21:36

    Bookmark   March 9, 2014 at 9:33PM
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The framer has an unusual approach to headers. It appears they are all 2x12's even for 3 ft spans and placed immediately under the top plates for interior and exterior walls. Then he interrupts the single jack stud to support a horizontal 2x4 at the head of the opening (that only resists a lateral load) and then places a cripple stud above it to support the header.

This appears to be a regional technique or perhaps it is intended to save time at the expense of material and energy efficiency (an approach from the 80's). The approach I have seen used would require a 6 ft header to be at the window head to resist the lateral wind load with uninterrupted double jack studs for support.

At any rate, light wood framing is so redundant and oversized these headers are probably just fine unless this house is in a high wind zone in which case it will need wall tie-downs, rafter ties and reinforced long span headers.

If any of these openings are for 6 ft+ swinging doors the 2x4 header should be reinforced.

    Bookmark   March 10, 2014 at 8:40AM
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The photo above shows a proper header installed to carry a load down into the foundation. The first photo by the OP shows solid blocking, rather than a header. Very odd framing as has been said.

    Bookmark   March 10, 2014 at 9:03AM
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So the verdict is in and...the framing for the window in the MB will have to fixed because the 2x4s that support the big block (I'm assuming this is the header) have to be directly underneath it and go all the way to the floor just like all the other ones, which was mentioned here. As far as the window install, DH had it looked at by his Dad and another friend who builds homes and they said it all looked good. This is all DH needed to hear, so he is against fixing any of it. And I don't know if I'm considered to be in a high wind zone but I'm in a hurricane zone near (but not ON) the Louisiana Gulf Coast. Ticks me off that I paid extra for higher efficiency windows instead of builder grade and the bad install will make that investment a waste of money. Thanks again for all the input.

    Bookmark   March 10, 2014 at 10:19AM
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I don't mean to offend you; you obviously are trying to learn a difficult subject in a short time with conflicting advice and I commend you for it. But as an experienced architect it is frustrating to deal with such strange ideas about building construction

The energy performance of your windows should not be affected by the configuration of the flashing.

If you are in a coastal hurricane zone you are in a very high wind area that would be classified as a "severe exposure" area due to wind driven rain. The 2 attached window installation details are for normal and severe exposures.

All professional standards for such an area recommend fully wrapping of all rough openings with flexible flashing before installing the window and layering of the house wrap in shingle fashion at the head with a slot for water drainage below the sill. A further optional step would be to bring the sill pan flashing apron out between layers of the cladding.

You haven't shown us enough for us to know for sure if any of that was done but it doesn't seem that it was.

The risk in using a flashing system designed for a low-rainfall, low-wind climate in a severe exposure hurricane area is that water is more likely to get into the wall framing and eventually the interior of the house which can be expensive to repair and bad for your health. So the potential cost is in the future not now.

What is really strange is that the local building department would not insist on higher waterproofing standards.

But you and your family know the local climate and if you don't get a lot of wind driven rain, you will probably be fine.

    Bookmark   March 10, 2014 at 12:35PM
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Just wanted to pipe in that over here, while those gaps in your sheathing are a bit too large, we do gap them intentionally to account for thermal changes in the wood (expanding and contracting). That being said, it's about 1/8". This prevents the boards from pushing on each other and causing buckling later on. The gaps are covered in house wrap (tyvek, etc.) and not sealed as the sealant would negate the expansion joint.

Also, Tyvek is a pretty good wind break for these size gaps...I tried blowing through my own tyvek and couldn't. Not sure the mph of my lungs, but it's certainly not letting much air flow in once it's covered in siding, and does allow the moisture that may develop in the walls to vent out into the atmosphere easier.

    Bookmark   March 11, 2014 at 4:46PM
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I've used "advanced framing" headers to maximize thermal efficiency. Even if two dimensional headers are specified by the engineer, I keep them to the exterior to allow for rigid board insulation to the interior.

Since window flashing has been given the thumbs down by the local experts, one can at least hope your builder will foam the gaps between the windows and the framing. Or will it be the old standby of fibreglass?

Advanced framing headers save on lumber and increase thermal efficiency. But not suitable for high-wind/seismic zones.

This post was edited by worthy on Tue, Mar 11, 14 at 18:29

    Bookmark   March 11, 2014 at 6:24PM
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The purpose of joint sealant is to allow movement of the joint while providing closure; it will not cause the panels to buckle. But the difficulty is in sealing an open gap with no backing because the sealant cannot be formed in the hour-glass shape that allows maximum movement and maximum adhesion.

Air may not pass through Tyvek but it can go around it because it is virtually impossible to adequately seal all of the perimeter and the lap joints.

The simple solution is to put blocking behind the sheathing joints which allows for full nailing of the wall panel perimeter which allows the panels to develop their full resistance to lateral forces and therefore be less likely to separate like a house of cards in high winds. The cost of this blocking is perhaps the cheapest form of insurance available in home construction.

IMO the resistance of contractors to the use of better construction techniques is primarily due to the inability or unwillingness to think in more than 2 dimensions. An example is the chopping up of jack studs by the OP's contractor as if gravity was the only force involved.

    Bookmark   March 11, 2014 at 9:14PM
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