Do You See Any Construction Problems With This Roof Framing? 6

[jfklein]

I am on the board of directors for small condominium in Canada. The building was built in 1979, it is wood-frame construction and has a flat (i.e. low-slope) roof.

Recently we had a roof consultant inspect the roof in preparation for replacement of the weatherproofing membrane, that covers the roof, next year. When looking at the framing below the plywood deck of the roof the consultant noticed what he described as questionable construction work and recommended that we hire a structural engineer to check it out and determine it's structural integrity.

The consultant made his observations of the roof framing from a hatch opening that penetrates through the roof structure making it possible to see below the deck. I have attached four photographs taken on opposite sides of the hatch opening, looking down the cavities between cross-strapping members that support the deck. On the photos I have indicated the consultant’s comments about the construction work.

My questions for this forum:

What do you think about the quality of the construction work shown in the photos, specifically the attachments between the components of the roof - the plywood deck, the tapered 2x4 cross-strapping members and the 2x10 joists?

Does it look like typical construction work for a wood-framed building?

Do you think the consultant’s comments about the structural integrity of the roof are justified?

 

[jfklein]

Kootk, "furring" strips got your point across just fine. In this case/application, I sometimes call them "sleepers".

To the OP, your inspector has raised some potentially valid concerns that require further investigation to be prudent. For starters, much better visual access to a representative sampling of the existing conditions would need to be provided (i.e. selective demolition and/or removal of finishes).

I’m told some inspection holes would need to be cut in the deck in a few locations to get a more complete understanding of the construction work on the sub-structure.

I would have thought that a boroscope would be used which would be far cheaper and easier to repair, since it could be done with only a small hole drilled through the deck.

 

[jfklein]

I like a note on drawings that says to fill all holes in joist hangers with specified fasteners, unless noted otherwise. To me, open holes in joist hangers is always a red flag. That being said, Simpson lists multiple capacities for some of their hangers depending on how many nails are used to install. In that case, you should be able to at least expect to to see symmetry of the nails and open holes in every joist hanger. Haphazard nails and open holes from one joist hanger to the next is again a huge red flag of possible shoddy construction and workmanship.

Thanks for pointing that out.

From the photos it looks like the holes in the hanger flanges aren’t used at all. Rather, nails are shot right through the metal of the flange into the supporting joist.

Also, one hanger has the top of the flange bent over the top of the supporting joist for some reason.

 

[LittleInch]

jfklein,

I'm feeling for you here and as you can tell I'm not a structural engineer, but dip my toe into these sort of posts every now and then.

The structural engineering business and users tend to be much more litigious than many other areas of engineering so that colours the posts of a lot of my esteemed posters and the reluctance of an inspecting engineer to say "Yes it's fine, no problem". Even when pressed they will not and cannot "guarantee" anything, because you pay them say $500, but the liability if it goes wrong is $500,000. This basically passes on the risk benefit judgement to you and your fellow directors. Enable makes some good points, but from what we can see, the structure looks in a good condition. And that is the conundrum now - anyone you hire who does an inspection will write a report which either recommends a whole new roof or remedial repairs which cost the same thing, or just recommend a more intensive survey to remove a section of roof either top or ceiling to ascertain the condition. The genie is unfortunately out of the bottle on the structural inspection now it's noted in a report from the roofing person. Genies are buggers to get back into the bottle....

You asked what sounds like a simple question about structural integrity.

For a 42 year old roof, this looks in excellent condition to me. No signs of sagging, rot or dodgy cut outs by workmen to lay cables or pipes. Now sure it might not be 100%, but most of the tapered joists seem to have at least one toe nail in. Note this in only based on 4 photos and no other details, so is a rather imprecise judgement.

If the joists can't go anywhere then why bother with nails in the hangers ( though there might be some from the underside?) and if the roof hasn't dipped anywhere a few nails missing from the hangers themselves don't seem to have made an impact.

So this becomes, IMHO, a simple economic vs BYA decision. Rip out what looks to be a perfectly good roof which has stood the test of time and spend upwards of $100K to move it from 70-80% integrity level to 95 to 100, or leave it alone. Maybe figure out where the joists actually are and when the membrane is replaced just nail the plywood down a bit more actually into the beams. Only if you actually need to replace the sheathing would it be worth doing anything more whilst you have good access.

Your (judgement) call.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[NorthCivil]

can the mods shut this thread down?

this isnt free-engineering-opinions-online.com

 

[jfklein]

jfklein,

I'm feeling for you here and as you can tell I'm not a structural engineer, but dip my toe into these sort of posts every now and then.

The structural engineering business and users tend to be much more litigious than many other areas of engineering so that colours the posts of a lot of my esteemed posters and the reluctance of an inspecting engineer to say "Yes it's fine, no problem". Even when pressed they will not and cannot "guarantee" anything, because you pay them say $500, but the liability if it goes wrong is $500,000. This basically passes on the risk benefit judgement to you and your fellow directors. Enable makes some good points, but from what we can see, the structure looks in a good condition. And that is the conundrum now - anyone you hire who does an inspection will write a report which either recommends a whole new roof or remedial repairs which cost the same thing, or just recommend a more intensive survey to remove a section of roof either top or ceiling to ascertain the condition. The genie is unfortunately out of the bottle on the structural inspection now it's noted in a report from the roofing person. Genies are buggers to get back into the bottle....

You asked what sounds like a simple question about structural integrity.

For a 42 year old roof, this looks in excellent condition to me. No signs of sagging, rot or dodgy cut outs by workmen to lay cables or pipes. Now sure it might not be 100%, but most of the tapered joists seem to have at least one toe nail in. Note this in only based on 4 photos and no other details, so is a rather imprecise judgement.

If the joists can't go anywhere then why bother with nails in the hangers ( though there might be some from the underside?) and if the roof hasn't dipped anywhere a few nails missing from the hangers themselves don't seem to have made an impact.

So this becomes, IMHO, a simple economic vs BYA decision. Rip out what looks to be a perfectly good roof which has stood the test of time and spend upwards of $100K to move it from 70-80% integrity level to 95 to 100, or leave it alone. Maybe figure out where the joists actually are and when the membrane is replaced just nail the plywood down a bit more actually into the beams. Only if you actually need to replace the sheathing would it be worth doing anything more whilst you have good access.

Your (judgement) call.

The problem is it is actually very difficult to answer the question ‘Is this roof structurally sound?’ because the structure of the roof is not visible. Even if as-built drawings of the original construction are available, it doesn’t guarantee that it was built that way or there hasn’t been any deterioration or damage since then.

The question can really only be answered with a certain degree of uncertainty. So, in order to get the degree of uncertainty down to an acceptable level, the engineer may feel they need to either see a certain amount of the structure which of course requires penetration into the roof, or recommend repairs that may actually not be needed, or both.

The direction it could go is wide open, from nothing needs to be done to replace all the hangers, install attachment plates between the joists and cross-strapping and re-do the nailing between the deck and plywood, and I think it depends to a large degree on which engineer is doing the inspection.

 

[dold]

The problem is it is actually very difficult [likely very expensive] to answer the question ‘Is this roof structurally sound?’ because the structure of the roof is not visible. Even if as-built drawings of the original construction are available, it doesn’t guarantee that it was built that way or there hasn’t been any deterioration or damage since then.

It is not possible for anyone to determine whether the entire structure is safe by poking their head through an attic access hatch and taking a few pictures. That's why literally everyone here is telling you to hire a local structural engineer to perform a *real* inspection if you are truly concerned with the roof on your building.

Get Engineer's opinion (a real, non-internet engineer) >>> You decide whether or not to act on it. You can always hire another engineer to get a second opinion.

Here is some light reading (18 threads worth): Miami Beach, Champlain Towers South apartment building collapse, Part 18

Perhaps a bit dramatic compared to your situation but maybe it will help you understand why engineers operate the way we do. I.e., toenails *possibly* missing from tapered sleepers, and joist hangers *possibly* installed incorrectly, *probably* won't lead to global collapse.

 

[LittleInch]

You can always partially kick this can down the road and build up a fund for roof replacement / deep inspection when it gets to 50 years old?

When stripping the current roof membrane off, if there are any visible signs of water penetration / rot / movement etc then stop and investigate that bit further. At the least you might be able to figure out what those random nails are which are poking through and whether there are other nails actually holding the plywood to the frames

The guys doing the roof work will be imposing loads on the roof that it never normally sees so they will tell you pretty fast if there is any undue deflection or damage that needs further investigation.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Factoter]

A question here is “what the heavens happened?”
-And-
Is there any evidence of structural problems?

There is no evidence of structural problems, there is evidence of inexperience and slop, and corner-cutting haste, which are problems if they become problems.
I can say that these shots show haste and slop, but no apparent weaknesses

 

[jfklein]

A question here is “what the heavens happened?”
-And-
Is there any evidence of structural problems?

There is no evidence of structural problems, there is evidence of inexperience and slop, and corner-cutting haste, which are problems if they become problems.
I can say that these shots show haste and slop, but no apparent weaknesses

Thank you for answering the questions I actually asked.

 

[ThomasH]

I'm only trying to gather as many opinions as I can. The ones I have so far have not been universally the same. In fact I have received one opinion from an engineer, based on the photos and the age of the building, that an inspection isn't even needed.

Are any of the opinions you have gathered based on actually visiting the site or are they all based on the photos? From what I can see in the thread you have one opinion based on seeing the roof, the roof consultants. And that recommendation was to consult a structural engineer. And you have received that recommendation in the thread also, what is stopping you?

As for an engineer being biased to recommend an extensive investigation. I can understand that you may feel worried that they will recommend repairs if they can do the repairs. But if you ensure that they only do the investigation, don't you think that can perform an unbiased investigation? They should be engineers, not contractors.

It seems to me that you are persistent in your questions, basically opinions for free . But you don't seem to like the advice to discuss this with a structural engineer, why? I would say that the cost for an inspection made by a structural engineer, that is the best case scenario here. And the worst case scenario is not repairs for $100,000.

 

[Factoter]

Why are the hangers bent?
—These are the incorrect hangers. They were installed after the carpenters hung the joists by an *apprentice* in a very dangerous and incorrect fashion, using an air nailer. The hangers were bent on installation to keep them from protruding, because they are too long.
Why is there separation at the joists?
—Because they were cut short.
Why is there deficient toenailing?
—The apprentice couldn’t toenail with the nailgun to save his life. But it was good enough to get the job done.
Why are nails protruding from the plywood?
— Apprentice tasked with nailing off plywood made a mess of it.

Are any of these above items structural engineering problems?
-Yes, No, Maybe. Ask an engineer.

 

[MacGruber22]

Jfklein, heed the warnings. You are being pushy. Further, if you are a registered engineer and take information from this site to make an opinion in the practice of structural engineering (that you are not competent in) related to this building, you are flirting with violating licensing ethics. Also, put the shoe on the other foot if it were a structural guy trying this with mechanical systems. You would tell them the same thing, to hire a mechanical engineer because it is too risky judging from photos and secondhand explanations.

I suggest you change your approach and ask about generalities with respect to building construction, and don't ask for specific and definitive opinions on your subject building.



-Mac

 

[wrantler]

When a contractor calls me up to have a look at something I take it pretty seriously...they do not usually call me for nothing. After all they build and see buildings everyday as their job so if something seems off to them I take that opinion very seriously.

I hope that nobody in the industry (client, contractor, engineer) would skimp on things that possibly place the future occupants of the bldg in danger. But then again I live in a world that money exists.

 

[jfklein]

Why are the hangers bent?
—These are the incorrect hangers. They were installed after the carpenters hung the joists by an *apprentice* in a very dangerous and incorrect fashion, using an air nailer. The hangers were bent on installation to keep them from protruding, because they are too long.
Why is there separation at the joists?
—Because they were cut short.
Why is there deficient toenailing?
—The apprentice couldn’t toenail with the nailgun to save his life. But it was good enough to get the job done.
Why are nails protruding from the plywood?
— Apprentice tasked with nailing off plywood made a mess of it.

Are any of these above items structural engineering problems?
-Yes, No, Maybe. Ask an engineer.

Thanks for your insights. This is exactly the kind of information I was seeking.

 

[jfklein]

Jfklein, heed the warnings. You are being pushy. Further, if you are a registered engineer and take information from this site to make an opinion in the practice of structural engineering (that you are not competent in) related to this building, you are flirting with violating licensing ethics. Also, put the shoe on the other foot if it were a structural guy trying this with mechanical systems. You would tell them the same thing, to hire a mechanical engineer because it is too risky judging from photos and secondhand explanations.

I suggest you change your approach and ask about generalities with respect to building construction, and don't ask for specific and definitive opinions on your subject building.

When a contractor calls me up to have a look at something I take it pretty seriously...they do not usually call me for nothing. After all they build and see buildings everyday as their job so if something seems off to them I take that opinion very seriously.

I hope that nobody in the industry (client, contractor, engineer) would skimp on things that possibly place the future occupants of the bldg in danger. But then again I live in a world that money exists.

Rest assured. I started looking for a structural engineer several weeks before starting this thread.