Roof Sagging

[John J. Beltham]

I am in the process of evaluating a house for possible purchase. While inspecting it I noticed that the roof was sagging. I crawled into the attic and noticed that a main support timber had failed and someone had attempted to brace it. You can see a photo here

This is not the roof in question but ithe picture depects exactly what I found in the attic. I plan on having a licensed roofing contractor evaluate the roof. The house is circa 1955 and built on a slab. I do not see any cracks in the stucco or drywall, just one small area that is sagging on the roof above where this timber is. I was just wondering what could cause this timber to fail?

[Edwin Pawlowski]

Leaks are a good start, moisture from poor ventilation are good starts. Poor construction and inadequate material can be factors. Be very careful if you are buying this place. If the roof was left in poor repair, so were other parts of the house. Be sure the price is right if you buy because you may need major repairs.

[Roger Taylor]

The remedy is as important as the cause. Cause could be many things, including insufficient rafter or bracing strength, or wood weakened by rot or moisture. Roofers in my experience know little of substructure and rafter sizing, bracing, and spacing. Also avoid "building inspectors" (no degree required). For this issue, get a competent structural or civil engineer with full knowledge of current codes for roof substructure building. They can tell you why rafter bracing failed, how it failed, and whether a support structure needs to be rebuild or redesigned. You'll find them in the yellow pages, and can pay them per visit or per hour. Well worth it, if you are planning to buy. Roger

[valvejob]

Probably defective timber, but it makes no nevermind.

You can brace it and level it and it will last forever so take the money you spend on inspectors and put it in bracing timber.

.

[Joseph Meehan]

I suggest Roger has the right answer.

[BobK207]

here

is not the

John-

I don't know how representative the posted photo is of the roof in the house that you are contemplating purchasing......

but from this photo the roof framing system looks to be missing some members....

Another guess here (& story from that guess) but I think you've got a site built roof truss system.

Sometime in the past someone removed the struts that go from what you are calling the "main member" down to rest of the house structure.

This allowed the "main member" to be over loaded & fail. After the sag was noticed, someone tired to repair the situation.

Another guess here....I think the repair will be pretty easy, install some temporary supports, true up the roof, sister the damaged memeber, install properly placed struts, remove tmep supports.

BUT to be certain.......

I would suggest getting a "roof engineer" out to have a look, a few $100's max & well worth it.

At least in my area there are civil / structural engineers who specialize in roof assessment (necessary if going from wood to tile). They have so much roof framing design / repair / retrofit that they can usually tell by looking at it (no calcs) what you need to fix it.

If my evaluation of the photo is correct your "main member" is actually an intermediate member placed at ~ mid rafter span such that small rafters (2x4's) could serve. It in turn needed braced with struts every 4' or so to a bearing wall below.

I have a very similar roof framing system that I would love to remove the struts to open up the attic space but they're need to support the roof. :)

cheers Bob

[RickH]

here

is not the

The hardest part will be getting a new lam beam up there to sister next to or onto the bad one. You may need to make a hole in the gable end wall then slide it all the way into the attic, unless you are lucky enough to have a side vent or window to go through. In either case go full length so the beam ends sit on wall tops under verticle studs, and that your new beam is rated for the length/weight of the roof.

[John J. Beltham]

Thanks to all who responded. I found the perfect solution to the problem. I told the realtor I did not want the house. Two days later I found the perfect house that all I have to do is move into it. I made an offer on it last night.

[aemeijers]

Chuckle. Sometimes walking away is the best solution- we all only get so many years of productive life, and just like you have to learn to choose your battles, you also have to learn to choose your projects.

There are days I wish I had walked away from this place, and gone just slightly further into debt to buy a place without a 'to do' list. No major problems, and the basic structure is square and solid. But all the piddly little stuff is turning out to be more of a time and money sucker than I planned on, and I'm finding that even simple stuff takes WAY longer than it did when I was a kid. The brain still has the knowledge, but after 20-some years away from hammer-swinging, the seem to have trouble remembering.

With repairs and upgrades, I've already spent as much as I would have for a fixed-up place or newer place, and could easily spend another 10-15k. But then I would have more in the place than I could sell it for, what with the recent market downturn.

aem sends....