Roof Makeup Construction Drawings vs. Actual Build

[saveasteading]

2 hours ago, torre said:

ask if he's happy it's constructed as designed? 

I agree. 

Perhaps allow it to be informal.

 

It is surprising that the architect (Architect?) chose a beam specification. Unless he has seen the same span before and is repeating it. Or maybe there is a ready reckoner for them.

But the slates are an issue and so there will be other issues too.

Maybe it can be propped and the packing replaced half at a time.

[Gaf]

3 hours ago, saveasteading said:

I agree. 

Perhaps allow it to be informal.

 

It is surprising that the architect (Architect?) chose a beam specification. Unless he has seen the same span before and is repeating it. Or maybe there is a ready reckoner for them.

But the slates are an issue and so there will be other issues too.

Maybe it can be propped and the packing replaced half at a time.

 

If I’m reading you right, he was an actual architect Architect (RIAI), not a technician, engineer etc.

 

Am waiting in a call back from surveyor on it.

 

[Gaf]

Looks a bit like the architect may have expected them to build it something like this:

 

[Gaf]

I don’t know what to think at this stage.

 

Building surveyor came back. Has no concern with the slate shims as they are, basically leave them as is.

 

Said the piece of timber between the wooden ridge and the steel beam has no function. Said the fact it isn’t clear whether this piece of timber is touching the ridge or not is nothing to be concerned about. Have asked for clarity over what he feels the beam is for then.

 

Have both responses in writing…

 

 

[saveasteading]

6 hours ago, Gaf said:

Said the piece of timber between the wooden ridge and the steel beam has no function. 

Well....it looks to me that the ridge is not touching the horizontal timber, at the end we see anyway. To that extent it is not functioning.....yet.

But that results in the rafters not bearing on the steel beam at all, i.e. the steel isn't functioning either...not yet anyway.

 

In life, the rafters will spread out as discussed earlier, and drop. Then they will bear on the timber and steel.

 

I'm saying no more as your advisers have the advantage of seeing the real thing. I'm just concerned that they understand what they are looking at.

 

I would pack mortar between  and around the slates as a minimum.

[Gaf]

8 hours ago, saveasteading said:

Well....it looks to me that the ridge is not touching the horizontal timber, at the end we see anyway. To that extent it is not functioning.....yet.

But that results in the rafters not bearing on the steel beam at all, i.e. the steel isn't functioning either...not yet anyway.

 

In life, the rafters will spread out as discussed earlier, and drop. Then they will bear on the timber and steel.

 

I'm saying no more as your advisers have the advantage of seeing the real thing. I'm just concerned that they understand what they are looking at.

 

I would pack mortar between  and around the slates as a minimum.

 

Yeah mate I really don’t understand it. At even my own basic level of knowledge I don’t understand how the wood over the beam has no function, it’s the only potential contact between the roof and that steel beam. If it has no function then that effectively means the steel beam has no function and that roof if being held up by the outer walls with no joists in place.

[saveasteading]

59 minutes ago, Gaf said:

 I really don’t understand it.

But you do. It's the supposed experts that either don't understand or are covering for each other.

[Mike]

Catching up with this after some time away, if this is the end of the ridge then it doesn't look good.

 

In the absence of an alternative solution, the top of the rafter should be notched over the beam (or a timber sitting on the beam), so that notch transmits the load from the roof vertically onto the beam. The timber ties beneath the beam are normally there to stop horizontal movement - that is, to keep the notches in their intended place on the beam - not to stop the rafters sliding down towards the wall plates which, they will otherwise tend to do.

 

I would strongly suggest that you get a Structural Engineer involved before proceeding.

[torre]

7 hours ago, Mike said:

strongly suggest that you get a Structural Engineer involved

Agreed, pay one to visit the site for a couple of hours. If you're super lucky someone qualified like @Gus Potter may point you in the right direction first.

 

You've got an off the shelf ridge beam design from an architect, who hasn't drawn it that clearly and isn't taking much responsibility, then it hasn't been constructed as designed, and now your surveyor doesn't seem to fully understand or can't explain to you the design or construction.

 

Nobody is trying to worry you unnecessarily, but a couple of hundred pounds spent now could be a wise investment

[Gaf]

Cheers again lads. And 100% @torre I appreciate the info from everyone and don't take it as unnecessarily creating worry 👍

 

I got a visit to the site with the building surveyor. First thing he mentioned was the the size of the rooms meant, in his view and experience, the steel wasn't even needed and probably shouldn't have even been installed (one is 3.2m2 room, other is 4.3m2 room). His only gripe was wondering why it was installed if the timber ridge beam wasn't resting on it. He said best approach is to email the builder and ask him to confirm the roof is sufficiently supported so that I have it in writing, so if something happens down the line I'll have comeback. Was 50:50 about this and just thought why not just get it 100% now.

 

Builder ended up arriving on site as we were looking. It had been blocked up in the interim so we couldn't get up to get a proper look. BS spoke to the builder for clarification. Builder said it was a slight bend in the end of the timber ridge beam that made it look like it's not resting on the flatter timber - he said his joiner/carpenter did it and told him it was resting on the beam.

 

Surveyor seemed perturbed initially when querying why the steel was even installed but also took the builders word the timbers were in contact throughout.

 

Only afterwards I managed to stick my phone on a stick and squeeze it up into the upper roof part and get slightly blurry images (attached). It looks like there's a few mm gap between the timber ridge beam and the timber lying on the flat near the end of roof (original photo end) but there's no gap at the other end (second photo).

 

To date, there have been four 'issues' I've had to raise so far with all of them getting remedied - one was sizeable enough (two days work for a few men to fix but it was on site decisions being made instead of sticking to the construction drawings). I'm trying not to be that PITA client but I find it challenging when my own BS is saying it's OK. I think I'll have to put my big boy pants on and approach an SE before much more work gets done on site.

Edited September 24 by Gaf

[Iceverge]

I've skimmed the thread. 

 

I think the carpenters have a fundamental misunderstanding of how a roof works.

 

 

This is what they should have been aiming for. A notch on the joist top so there's no horizontal forces. Everything is very simple, just up and down loads. 

 

The ridge beam takes 2/3 of the total weight of the roof though and needs to be very strong and well supported at both ends.

 

 

Here's what they though they were building. 

 

Collar ties or more regularly ceiling joists keep the rafters from trying to do the "splits" and push the walls outwards. Notching at the top is not the correct thing to do as it's a horizontal load there rather than vertical. 

 

 

[Iceverge]

I've repeated some of what's been said above. I might be doing more here. Too lazy to read it all. 

 

However you do have an issue. 

 

 

The top of those joists will want to move down as they're just there by nails. In a few years and they'll slide down on the nails and spread the walls. It won't fall down but you might get a sagging roof and cracking walls. 

 

 

My solution would be to strip the roof membrane and top layers of battens and install joist hangers on the ridge beam like below. 

 

 

 

The ridge beam would become a load carrying member so must be in firm contact with the supportive RSJ below. This may need more fixings. A SE would advise. 

Edited September 24 by Iceverge

[Iceverge]

You seem to have abandoned the as drawn insulation method too. 

 

What is you plan now? 

 

 

[Dave Jones]

On 23/09/2024 at 08:25, torre said:

You've got an off the shelf ridge beam design from an architect, who hasn't drawn it that clearly and isn't taking much responsibility,

 

what a shocker lol

 

As others said get an SE in for 20 mins, send the architect the bill. If he dont pay start a complaint with their professional body. The paperwork alone will cost him more than an hours of SE time.

[Gaf]

Called ten engineering companies in the area flagged as including SE. Three SE’s may have capacity to have a look. Rest are not taking on work due to being too busy, only do consulting, or only do design with no on site surveying.

 

Awaiting calls back tomorrow 🤞 

[Gus Potter]

Best to ask now when you can remediate any issues easily. In your first post there is a screen shot of the roof spec? a mention of timber sarking. Is this missing?

 

 

@Gaf your photo of September 17 shows a higher part of the building behind.. with gabled openings?

On 23/09/2024 at 08:25, torre said:

Agreed, pay one to visit the site for a couple of hours. If you're super lucky someone qualified like @Gus Potter may point you in the right direction first.

Thanks for the kind words. However many of the posters have discussed a lot of the individual aspects of the works and made some great points. No point in me repeating as they have done a top job.

 

Looking at the photos and assuming they are of your job I seems to me that you must have had some SE input?

 

In the round though I would ask yourself / recognise and look at things in the round.. yes we have changed some bearings (slates as packers) and probably some of the connections.. but the really important question is.. have we done something that compromises the overall stability of not just the new bit but the old bit also.

 

I'm happy to chip in more but need a lot more info before I do.

 

If I was to come and look at your job I would take the grand tour of the house.. figure out how it stands up as existing. Then look at the new bit. Does it add both horizontal and downwards loads to the existing house found. If we add load to the old house founds and any existing lintels can they cope?  If we knock a hole in the existing house to get to the new part how does that impact on the structural stability and so on. The sarking is important here.

 

I think you need to be extra cautious and not pelt the Architect!. Often on a job the builder get's the "Client's ear" while cuttting corners at your expense!

 

Get an SE in.. pay 300 - 400 quid for a once round.. it will be the best money you spend!. Often I can justify my fee by pointing out things the builder has cut corners on that that are nothing to do with SE work. Then there is a bit of negotiation so no one falls out.

 

 

Edited September 25 by Gus Potter

[saveasteading]

1 hour ago, Gus Potter said:

Often on a job the builder get's the "Client's ear" while cuttting corners at your expense!

Very true.

 

1 hour ago, Gaf said:

Called ten engineering companies in the area flagged as including SE. 

A lot simply won't want the hassle of this, with the inherent risk of arguments and claims down the line, for a smallish fee.

[Gus Potter]

56 minutes ago, saveasteading said:

A lot simply won't want the hassle of this, with the inherent risk of arguments and claims down the line, for a smallish fee.

And that statement is unfortunately true.

 

One of the main reasons is that Clients do not recognise the value of an expereinced  Architect,  QS', or SE's for example.. but they will quite happily pay their Solicitor / Lawer £300 - 500 an hour to do conveyencing. As a designer from time to time I see what is tantamount to negligance from the legal profession.

 

For all on BH.. if you want to buy a plot I can tell you that you should get your design team lined up at the start of the land purchase process. Often we can spot things that could reduce the price for the land by a good amount.. and now we have washed our face and can often be in credit design fee wise.

 

With the new CDM regs, environmental regs and so on you need to be cost aware and not rely soley on legal advice.

 

Claims. Well the motto is don't do a daft design. Make sure your Client knows what they need to do and their duties. If the Client goes off and does their own thing.. by say taking the builders advice then hey ho!  AND this folks is often is often what folk on BH do and find themselves in a mess. Seriously there are so many folk that come on BH saying.. we changed this etc..and now we are in trouble.

 

 

Edited September 25 by Gus Potter

[Gaf]

3 hours ago, Gus Potter said:

Best to ask now when you can remediate any issues easily. In your first post there is a screen shot of the roof spec? a mention of timber sarking. Is this missing?

 

 

@Gaf your photo of September 17 shows a higher part of the building behind.. with gabled openings?

Thanks for the kind words. However many of the posters have discussed a lot of the individual aspects of the works and made some great points. No point in me repeating as they have done a top job.

 

Looking at the photos and assuming they are of your job I seems to me that you must have had some SE input?

 

In the round though I would ask yourself / recognise and look at things in the round.. yes we have changed some bearings (slates as packers) and probably some of the connections.. but the really important question is.. have we done something that compromises the overall stability of not just the new bit but the old bit also.

 

I'm happy to chip in more but need a lot more info before I do.

 

If I was to come and look at your job I would take the grand tour of the house.. figure out how it stands up as existing. Then look at the new bit. Does it add both horizontal and downwards loads to the existing house found. If we add load to the old house founds and any existing lintels can they cope?  If we knock a hole in the existing house to get to the new part how does that impact on the structural stability and so on. The sarking is important here.

 

I think you need to be extra cautious and not pelt the Architect!. Often on a job the builder get's the "Client's ear" while cuttting corners at your expense!

 

Get an SE in.. pay 300 - 400 quid for a once round.. it will be the best money you spend!. Often I can justify my fee by pointing out things the builder has cut corners on that that are nothing to do with SE work. Then there is a bit of negotiation so no one falls out.

 

 

 

Really appreciate your post. I’m on my phone so harder to get a decent response in but I’ll try (and try keep it concise!).

 

• Whole house is a new build.
• “Storey and three-quarters” was specified on planning.
• All walls (internal and outer leaf) are block. Outer walls are double leaf with 150mm cavity.
• This whole post relates to two rooms in particular  (~10m2 and ~19m2) both with vaulted ceilings. These rooms are circled in blue on the attached (I don’t want to upload the higher res PDF drawings as the architects name is on them but can get higher res plans from PC tomorrow).
• These two rooms had the same construction drawing detail for their roof/ceiling. Steel beam as the ridge beam (attached).
• Builder has built both roofs differently than specified on the drawings. He has a timber ridge beam that as best I can tell is only nailed to the rafters. This timber ridge (sort of) sits on another timber, with this piece of timber sitting on the steel beam (close up photograph attached). The timber ridge beam is not fixed to the timber that it sits on, and this piece of timber is also not fixed to the steel beam. 
• Builder has the steel beams sitting on slate shims, with the slate on padstones.
• The slates are not on the house yet. So far only a material looking black felt with what I think are counter battens are installed (attached photo). No wooden sarking board is installed.
• I can provide more specifics but don’t want to go OTT with detail (maybe I have already!).

 

In terms of professionals involved:

• We hired a registered Architect (RIAI) to do our construction drawings.
• Was lining up an SE until the architect said our house design was not complex and he was qualified to design, specify, and sign-off on the structural elements. I have it in writing that he has formally given design sign-off on his drawings that include all structural steel.
• For Building Control in Ireland, three professionals are registered as being qualified for certification of the build stages (architect, engineer, or chartered building surveyor CBS).
• We opted for CBS as he is known to is, is local to the area, and helped a lot with managing the local authority for our planning permission stage. 
• Likely now a mistake not to still get an SE involved. As you mentioned, we didn’t know any better but weren’t actively trying to skimp on this. The architect firm is very well known in the area so we felt we could trust his confidence on not needing an SE.
• I absolutely understand an SE may want nothing to do with this at this stage. Whilst I’m primarily concerned about the roofs on these two rooms I plan to ask for a full house survey so at least hope that would make it financially worthwhile. Fingers crossed.

100% agree, I’m not sure banging on the architect’s door about this is fair. If the builder thought the design wasn’t detailed enough to build it then in my book you make a phone call to get more detail instead of building it a different way. Bar asking to add in two skylights way before any roof work was even near starting, we have thankfully made no changes whatsoever to the house so any deviations from the drawings will be 100% on the builder.

 

I’ll be pursuing the SE route and will be happy to pay their fee. In the interim, again really appreciate any steer on this. I’m particularly conscious the builder plans to start the slates next week and I want to have some kind of confidence asking for that work to be paused until an SE can inspect.

Edited September 25 by Gaf

[Gus Potter]

1 hour ago, Gaf said:

Really appreciate your post. I’m on my phone so harder to get a decent response in but I’ll try (and try keep it concise!).

 

• Whole house is a new build.
• “Storey and three-quarters” was specified on planning.
• All walls (internal and outer leaf) are block. Outer walls are double leaf with 150mm cavity.
• This whole post relates to two rooms in particular  (~10m2 and ~19m2) both with vaulted ceilings. These rooms are circled in blue on the attached (I don’t want to upload the higher res PDF drawings as the architects name is on them but can get higher res plans from PC tomorrow).
• These two rooms had the same construction drawing detail for their roof/ceiling. Steel beam as the ridge beam (attached).
• Builder has built both roofs differently than specified on the drawings. He has a timber ridge beam that as best I can tell is only nailed to the rafters. This timber ridge (sort of) sits on another timber, with this piece of timber sitting on the steel beam (close up photograph attached). The timber ridge beam is not fixed to the timber that it sits on, and this piece of timber is also not fixed to the steel beam. 
• Builder has the steel beams sitting on slate shims, with the slate on padstones.
• The slates are not on the house yet. So far only a material looking black felt with what I think are counter battens are installed (attached photo). No wooden sarking board is installed.
• I can provide more specifics but don’t want to go OTT with detail (maybe I have already!).

 

In terms of professionals involved:

• We hired a registered Architect (RIAI) to do our construction drawings.
• Was lining up an SE until the architect said our house design was not complex and he was qualified to design, specify, and sign-off on the structural elements. I have it in writing that he has formally given design sign-off on his drawings that include all structural steel.
• For Building Control in Ireland, three professionals are registered as being qualified for certification of the build stages (architect, engineer, or chartered building surveyor CBS).
• We opted for CBS as he is known to is, is local to the area, and helped a lot with managing the local authority for our planning permission stage. 
• Likely now a mistake not to still get an SE involved. As you mentioned, we didn’t know any better but weren’t actively trying to skimp on this. The architect firm is very well known in the area so we felt we could trust his confidence on not needing an SE.
• I absolutely understand an SE may want nothing to do with this at this stage. Whilst I’m primarily concerned about the roofs on these two rooms I plan to ask for a full house survey so at least hope that would make it financially worthwhile. Fingers crossed.

100% agree, I’m not sure banging on the architect’s door about this is fair. If the builder thought the design wasn’t detailed enough to build it then in my book you make a phone call to get more detail instead of building it a different way.

 

I’ll be pursuing the SE route and will be happy to pay their fee. In the interim, again really appreciate any steer on this. I’m particularly conscious the builder plans to start the slates next week and I want to have some kind of confidence asking for that work to be paused until an SE can inspect.

Hello Gaf.

 

That's some response from a phone! I've picked out some bits from your text and quoted in italic blue.. it's late here and off the day job so forgive typos grammer etc.

 

By way of encouragement and hope this helps.

 

"I’m not sure banging on the architect’s door about this is fair" agree with this.. keep it low key.. that last thing you need is a full blown barny.

 

"Builder has built both roofs differently than specified on the drawings." That's the rub really. I have chipped in as an SE and designer to say.. hey lets look at the overall picture for example in terms of stability.

 

"Was lining up an SE until the architect said our house design was not complex and he was qualified to design, specify, and sign-off on the structural elements" Now that may be the case. Your Architect may have used the small buildings type of guidance and so on. It sounds like the Architect has lots of experience so that is good. I'll not go into detail here on this aspect as I use my own name on BH.

 

"I’ll be pursuing the SE route and will be happy to pay their fee." Give your Architect the opportunity to respond first before involving an SE. This is the protcol. Take your posts on BH, format them and send to the Architect. Write in a fiendly manner and informally. The key here when writing is that you are not expected to be an informed Client.. you are a self builder.. so don't try and be smart technically .. just state your case the way you see it. Which is.. I have paid for something that is shown on the drawings and this has not been delivered or words to that effect. You can evidence this by way of photographs.  Do not get emmotional.. just lay out the basic facts.. do not give your own technical opinion at any time however tempting that may be!

 

Clearly the building work is ongoing thus time is "of essence" and this term has legal and contractual meaning so make sure you include this phrase or equivalent to where you live.  I assume the same legal terms apply in Ireland.

 

That's all for now. If you get stuck then give me a call on 0771 308 1597.. text me first as I tend to filter calls and I'm a bit deaf. Happy to chat for 15 min but no more! Yes I know I should not give my number on BH but it's splattered all over the internet anyway!

 

 

 

Edited September 26 by Gus Potter

[Gaf]

7 hours ago, Gus Potter said:

Give your Architect the opportunity to respond first before involving an SE. This is the protcol.

Thanks again for your post. Appreciate the advice from someone in the field.

 

Just before touching base with the architect on this, the reason I was going straight for an SE is that there was an issue where seven dormer roof structures were built differently than on the drawings. There was a little kerffufle where the builder felt the drawings weren’t clear and the architect holding firm that they were clear (as you mentioned, I took a non emotional position and stuck to facts but I think events not of my doing has lost some goodwill from the architect). It was two days of work to have them changed back to match the drawings at the builder’s expense. The architect took the position that if anything is done on site differently than on the drawings then it is on our certifier now (our chartered building surveyor) to sign off on these. I believe I will just get this same response now from the architect, effectively “We designed it as A and your builder has done B. We’re not certifying the work on site so this is a matter for your certifier”.

 

 

 

 

[Gaf]

Coming back to this. Long story short, only a small number of SEs available, quickest would have been 6+ weeks wait and sought €1k+VAT just to inspect the steel, wouldn't include inspection of anything else or do a walk through with us. One SE actually recommended our BS and said if our BS was signing off on it and said it was OK, then the SE said he would trust it. Our BS got the builder to supply confirmation in writing acknowledging they built it differently than the plans and that they were standing over the structural stability of it. Not perfect, and may not be what the more knowledgeable here would accept but we felt very stuck with how to proceed with varying levels of advice.

[saveasteading]

1 hour ago, Gaf said:

how to proceed with varying levels of advice

Does a steel look suitable? With experience and in a conventional construction a knowledgeable hunch will likely be about right.

 

In the days of manual calculation by slide rule, we had to "guess" a steel size then check for the loading, then repeat. 

Guessing well saved a lot of time.

Choosing a heavier steel cost the client money, and I'm glad to say, was frowned upon.

 

OK I'll tell you.

Span divided by 18 for the height of the beam, and choose  a stock section, or apply an experienced hunch.

[Gaf]

According to the builder, joinery, and our BS, the architect went OTT on the steel to cover himself. Builder and joiner said they've never seen that size of steel put in for that size of a roof.

[saveasteading]

2 hours ago, Gaf said:

the architect went OTT on the steel to cover himself

Your money, his convenience is a common occurrence. But it saved the fee of an SE so no worse off.....but a waste of resources/ not sustainable design.