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Rotten studs on 4x2 laid on edge roof structure


Andre Milbradt
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This is my first post and at the same time something that you might not have seen before. My wife and I made an offer (that got accepted) for a home built in 1954 that features an unusual roof construction.

The problem is that our home inspector found out that parts of the roof structure are rotten, but we are having a hard time evaluating what that means to us in terms of it being a deal breaker or not.

Here's a photo of the ceiling.

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tn_201011171316_CeilingDetail.jpg

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The roof structure consists of 4x2 Cedar studs laid on edge. The studs are running from the inside to the outside and are supported by 5 beams. So the the ceiling studs plus the beams are basically the roof structure.

The problem is that in 1997 the roofer installing a torch-down roof did not wrap the roof layer around the edges of the roof/ studs. Instead he just put a cap on the fascia board. Now whenever the gutters got clogged up water did drain over the fascia board, but also penetrated into the the roof studs.

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tn_2010111713940_PoolingWater.jpg

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This caused rot to the very end of the roof studs as shown here.

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tn_20101117131223_RottenStuds.jpg

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We are having another look today, but the challenge that we are facing is how to determine if a stud is affected by rot or not and how much it is affected (without taking off the torch-down roof or cutting into the studs). It's easy to tell for the ones that are rotted through all the way (like shown in the picture above), but rather hard to tell for the ones that are not as badly affected.

I'm looking for any kind of advice or opinion that helps us making a call on this being a deal break or not.

Thank you for your help,

Andre

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One of the many things I would consider is whether that roof is very well insulated. It looks like what you are calling "studs" are 2x4s laid face to face as a combination ceiling/roof deck. Is there insulation anywhere in the assembly? I suspect it's minimal or none, perhaps a thin layer under the roof membrane. This might be a golden opportunity to rebuild or replace the assembly with something that (a) won't have water problems, and (b) will minimize heat loss. There are several good inspectors on this forum from the Seattle area. I would get someone to clarify this for you. I would also ask for 12 or more months of utility bills so you can evaluate the heating cost. I know it's not that cold around here, but it isn't tropical most of the time.

To answer the question that you did ask, someone with the right moisture meter(s) could spend some time to determine what's wet and what's not, and could probe for soft areas. It would be hard to be conclusive about exactly where you stand without removing the membrane.

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Bring a step ladder and feel the undersides of the wood for dampness. You are correct, probing is difficult without doing damage but a thin blade could be used between the 2 x's. Infrared imagery could be an option, but this will simply tell you if there is moisture, and appearance and feel can do that too.

Can that eave be shortened and a conventional gutter be installed?

As you probably know, there is minimal insulation in that ceiling. However, I see a raised area inboard of the overhangs, so they may have laid foamboard down under the new roof cover. This creates a soft surface and there can be problems with the membrane bubbling or sagging, especially around skylights and vents.

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Assuming the last pic is indicative of the worst damage it isn't a very difficult fix, but it won't be cheap. Remove the gutters and fascias, peel back the EPDM roofing (in my neck of the woods 13 years exceeds its service life anyhow), and cut back the overhang far enough to remove the rotted end grain, spot treat small areas of remaining rot with an epoxy stabilizer, and use a solution of oxalic acid to remove the black stains if you prefer to keep the natural finish. Skip the acid if you can live with paint.

Before resurfacing the roof you really should consider adding some insulation, with the little I can see of that building in your pics it is going to be an energy hog. If it were mine, it would get at least 2 perpendicular layers of 2 inch rigid foam insulation with the seams staggered, capped with commercial base sheet (a 2 1/2" foam panel with OSB glued to one side), and roofed in rubber or PVC. Obviously this would include new fascias and proper termination bars for the roof membrane. This is not a job your average residential roofing company will be capable of, and in my area at least would require a commercial roofer.

EDIT: This is what happens when I answer the phone in the middle of posting. Pushed to the end of the line.

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This is my first post and at the same time something that you might not have seen before. My wife and I made an offer (that got accepted) for a home built in 1954 that features an unusual roof construction.

The problem is that our home inspector found out that parts of the roof structure are rotten, but we are having a hard time evaluating what that means to us in terms of it being a deal breaker or not.

Here's a photo of the ceiling.

Click to Enlarge
tn_201011171316_CeilingDetail.jpg

44.86 KB

The roof structure consists of 4x2 Cedar studs laid on edge. The studs are running from the inside to the outside and are supported by 5 beams. So the the ceiling studs plus the beams are basically the roof structure.

The problem is that in 1997 the roofer installing a torch-down roof did not wrap the roof layer around the edges of the roof/ studs. Instead he just put a cap on the fascia board. Now whenever the gutters got clogged up water did drain over the fascia board, but also penetrated into the the roof studs.

Click to Enlarge
tn_2010111713940_PoolingWater.jpg

51.39 KB

This caused rot to the very end of the roof studs as shown here.

Click to Enlarge
tn_20101117131223_RottenStuds.jpg

42.62 KB

We are having another look today, but the challenge that we are facing is how to determine if a stud is affected by rot or not and how much it is affected (without taking off the torch-down roof or cutting into the studs). It's easy to tell for the ones that are rotted through all the way (like shown in the picture above), but rather hard to tell for the ones that are not as badly affected.

I'm looking for any kind of advice or opinion that helps us making a call on this being a deal break or not.

Thank you for your help,

Andre

Interesting. You had the wisdom to hire a home inspector and he has rendered his service to you but has left you with questions even after he's seen the house with his own eyes. You've come to this home inspectors forum thinking that the answers will be found here.

Given the limitations on what an inspector can say with nothing more than photos, I'd suggest that you use this forum to find an inspector who can visit you onsite, review the situation, answer your questions to your satisfaction and basically give you the service that you should have received already.

From the looks of those photos, that's what you need. There could be major issues.

Marc

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Hi,

I doubt that this deterioration has occurred just since the 1997 reroof; it's probably been occurring since the first cover began leaking at the perimeter. My experience says probably since at least the late 60's.

Every one of those 2 by 4 roof members will have some rot in them. What you can't see is the incipient rot. Incipient rot occurs in the early stages of infestation. The wood will look and feel solid and appear to be rot-free but it isn't. Incipient rot extends ahead of the intermediate and advanced rot stages; so, if you are seeing intermediate rot and advanced rot in the ends of those members, you need to conclude that incipient rot has moved a substantial distance inward. If it reaches the connection between the roof members and the top of the wall framing, it can extend into the walls as well.

The good news is that between rains when the wood dries out the rot goes dormant and this can slow its progression signficantly. The bad news is - it rains a lot here. The other bad news is that dampwood termites and carpenter ants love that kind of construction.

I agree with David: it's probably pretty poorly insulated. These usually have a layer of heavy cellulose material beneath the cover. I wouldn't exactly call it "insulation" - wadding seems a more appropriate term but I don't know what it's actually called. This material usually begins a couple of feet inboard of the perimeter so that the area at the perimeter can function as a gutter of sorts.

Personally, I wouldn't dink around with it; I'd tear the entire cover off, remove the eaves overhang at the wall plate, drill and insert Impel Rods in the whole thing) to kill the incipient rot; install a series of deep rafters on top of what's there, install insulation, install a deck and fascia, tapered foam on top for drainage, a new cover and gutters and then install a frieze, sheating and strip vents on the underside of the overhang.

That's me; others would probably approach it differently.

ONE TEAM - ONE FIGHT!!!

Mike

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That'd be me. Tear off roof covering, repair what I found, then all new roofing configured in whatever manner appropriate to prevent it happening again.

Personally, I wouldn't be horribly concerned with incipient rot; I'd figure out how bad it was when everything got stripped off, and either Repel or epoxy penetrate any nastiness I found.

Older house in Seattle probably has old growth timber, right? That's reasonably decay resistant material. If it wasn't, that place would've rotted away to nothing years ago.

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The problem is that our home inspector found out that parts of the roof structure are rotten, but we are having a hard time evaluating what that means to us in terms of it being a deal breaker or not.

Interesting. You had the wisdom to hire a home inspector and he has rendered his service to you but has left you with questions even after he's seen the house with his own eyes. You've come to this home inspectors forum thinking that the answers will be found here.

Given the limitations on what an inspector can say with nothing more than photos, I'd suggest that you use this forum to find an inspector who can visit you onsite, review the situation, answer your questions to your satisfaction and basically give you the service that you should have received already.

From the looks of those photos, that's what you need. There could be major issues.

Marc

Marc, without seeing the report or hearing what was said, I wouldn't be so quick to condemn the inspector. No offense, I see your point.

After identifying the concern, how far do you go in designing the repair? It's not an easy call to make, and the level or degrees of repair needed can't be determined by visual inspection, can it?

(BTW, those could be 2X6 or 8's, not that it matters much.)

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I doubt that this deterioration has occurred just since the 1997 reroof; it's probably been occurring since the first cover began leaking at the perimeter. My experience says probably since at least the late 60's.

In 1954 that would have been a BUR with gravel ballast, and probably the longest lasting roof on the building. That means it's had no less than 4 coverings in its 56 years and it needs a new one now well ahead of schedule. Ouch.

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Older house in Seattle probably has old growth timber, right? That's reasonably decay resistant material. If it wasn't, that place would've rotted away to nothing years ago.

True enough, but when that incipient rot finally reaches the interior and interior moisture that's permeating the underside of that wood roof begins to feed it, it's liable to take off like a monkey with a firecracker stuck up his butt.

ONE TEAM - ONE FIGHT!!!

Mike

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Thanks for the all the replies. I just checked back and I’m blown away by all the information you all supplied to me in the last couple of hours. Thank you.

With respect to my inspector, I’m actually quite grateful that he found this issue. I looked at the roof structure a couple of times myself and didn’t really see anything that concerned me, but I don’t posses any skills when it comes to judging these kind of things. He on the other hand actually tapped on the 2x4s with a metal stick and with that uncovered the rot by breaking through the bottom of some of the 2x4s (it was not visible from the outside prior to that). After he found the rot damage he instantly showed it to me. At the end of the inspection he suggested to have either a roofer or finish carpenter (or both) come out to further determine the amount damage that occurred and how much it would cost to fix it.

Today I have the superintendant of small, local builder come out to further inspect the damage as well as a roofer to give us a number for reinstalling the roofing layer on top of the fixed 2x4s. The reason I posted my question on this board is to get another set of opinions on how to address this issue and if we should just walk away from the deal if we cannot determine the full amount of rot damage. This home is an absolute dream home for us (we’ve been looking for the last 2-3 years), but it is on the higher end of our price range (some repairs factored in). So the question I’m pondering over is if 5 years from now we will feel that buying this home was either a great decision or a shot in the head.

Thanks for the suggestion on using a moisture meter. It’s something that we didn’t think of so far. In terms of shortening the eaves, that is the current plan to take off the grunt of the rot damage. We’re thinking that taking off 2-3â€

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True enough, but when that incipient rot finally reaches the interior and interior moisture that's permeating the underside of that wood roof begins to feed it, it's liable to take off like a monkey with a firecracker stuck up his butt.

ONE TEAM - ONE FIGHT!!!

Mike

That's interesting......I forget you have the moist/damp conditions all the time.

Have you ever seen this sort of thing accelerate into major structural damage?

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My recommendation would be to tear the roof covering off, or back depending on its condition, cut back the overhang to good material, and treat the rest with a wood preservative. Can't say I've seen an issue such as this lead to the rot spreading into the structure; not saying it isn't possible.

As an upgrade, it would be nice to remove the entire roof covering, add new insulation, and install a new cover from there.

I love posts such as this one. I get to see what other inspectors would call out, what methods of repair they would suggest, etc.

By the way Andre-- well written first post.

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Hi,

You've got to figure that spore has had decades to move inward to the structure. Pacific Dampwood Termites love this type of construction. They set up housekeeping in the end of a piece of wood and start moving inward, blocking up the entrances and galleries behind them with their own feces. They'll go until they can't find any more wet wood and then they'll bug out leaving the wood still rotting behind them.

The reason that I'd cut it back to the outside face of the plate is that from there Impel rods can be inserted into holes drilled into the end grain of each of those and as they dissolve borate will be pulled into the lumber and kill any spore that's gotten that far. You can still achieve almost the same look with a new roof frame on top of what's there and by installing a frieze over the cut ends at the wall plate and then using strapping and 3/8-inch T & G cedar on the underside of that deep roof overhang.

Air leakage up through a roof like that has to be significant and with those single-paned windows and deep overhangs keeping out the sunlight I'd expect there to be cold spots at the ceiling-to-wall joint along the perimeter walls that would provide just enough condensation to keep the spore moving without the borate being infused into the wood to kill it. to stop that air leakage up through that roof plane, I might install an IWS membrane over that old 2 by 4 deck before framing the new roof on top. If I did all that, I'd replace the windows with new double or triple-paned stuff and probably install a whole house air change system because now things would be a whole lot tighter.

I dunno; sometimes I over-think things.

ONE TEAM - ONE FIGHT!!!

Mike

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Insulation-wise, installing rigid board right over the roof deck will work nicely. Install 1x strapping over the foam (screwed to the existing deck with long screws) and then a layer of 5/8" CDX over that, and a new roof cover. The roof deck can be vented if desired. Obviously you get new, tall fascia boards as part of the deal.

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Insulation-wise, installing rigid board right over the roof deck will work nicely. Install 1x strapping over the foam (screwed to the existing deck with long screws) and then a layer of 5/8" CDX over that, and a new roof cover. The roof deck can be vented if desired. Obviously you get new, tall fascia boards as part of the deal.

There are foam insulation boards with densities high enough that you can walk directly on them. You can mop down or mechanically secure the base sheet directly to it.

Marc

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