Any building inspectors or engineers, need some help.

manda1205

We're currently having a rear extension done by my brother (currently foreman for large building company). So far so good, till Friday when building inspector came look at roof, which was fine, but he then pointed out that he wasn't sure if there was enough brickwork above the lintel on the end wall. He said he'd go away and look into it. My brother said he's gone to plan and has built lots of other properties this way with no problems with building control.
The lintel in situ is a IG lintel l1/s 100 2100, we have emailed them to ask them if there is a minimum amount of brickwork to be above them, but doubt we'll here till Monday.
Just wondering if anyone can give their thoughts/advice.

Here' a pic;
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The brickwork above is 25mm and the wooden plate is 75mm.
Many thanks.

Furts

I am professionally qualified to pass comment on this. Regardless of what IG may, or may not say, about this I would condemn this work.

The lintel should be bedded onto full length blocks, without the straight vertical joint seen each side of the opening. This is encouraging a future crack down each side of the opening.

The spreader course above the lintel comprises of cut blocks that are likely to be broken, cracked, or damaged.

Aircrete block manufacturers produce coursing bricks for use in these types of location. Indeed, these can be stronger than the main walls if strength is required in these locations. Here it may well be.

Finally, all lintels should be designed and scheduled for use - it is not always a simple visit to collect one from the builders merchants.

I have just built my own home - every lintel was designed, manufactured and delivered to my home for the specific loadings and locations. In my case by Catnic.

Your lintel may be under sized for the minimal spreader course above, and for the roof loadings - which I would be unaware of. Certainly, your lintel rings alarm bells to me. I would not accept it in my home.

I also wonder if the opening is correctly tied up the reveals...?

manda1205

So in your opinion, what is the solution, bearing in mind, the roof structure is nearly finished. My brother thinks worse case the lintel is dropped and re-inserted, is this what you would suggest? We have also ordered windows too. What a headache this is.
Edit to add, yes its correctly tied at every course.

southcoastrgi

it depends if BC consider the plate as "loading" if they do it should be a min of 150mm blockwork above it link here point 7

yes agree with Furts straight joints & cut blocks not good

manda1205

southcoastrgi wrote: »

it depends if BC consider the plate as "loading" if they do it should be a min of 150mm blockwork above it link here point 7

But that link means how much the lintel should overhang each side(and sit on top of the brickwork), not how much should be above it.

southcoastrgi

1. Point 7 (as i said) Lintels should have a minimum of masonry 150mm high between the flange and the application level of any form of loading.

manda1205

Sorry yes, you are correct. Oh S***! Is the only thing I can think at the moment.
So looks like it will need to go lower and we will have another window to buy and a spare one!

Furts

I cannot see what your roof detail is, but from the size of the roof timbers there is a considerable weight expected on the lintel. Reassure yourself that this lintel, at this span, will meet the anticipated loading.

It is apparent the work needs rectifying. A stronger lintel may also be required.

manda1205

The extension is 5 x 4m, the roof has a small flat section that sits underneath an upstairs window. As we are having 2 velux windows and because of the flat roof the engineer has specified triple rafts at all sides of these. It is a slate roof at 15 degree pitch (slate will be either cambrian or birkdale).
My brother did say maybe they will suggest a different lintel to put in.
I just hope its fairly easy to rectify, ie, not taking any of the roof off, or needing to buy another window.

manda1205

Im a bit annoyed that the architect or engineer, or even building control didn't pick this up earlier, as we were originally having 2 windows on that end wall, so would have been worse if we'd kept that. Should the engineer have specifed a different lintel if it was needed?

Furts

Cambrian will go down to 15 degrees but this is absolutely on the limits.

This is a roof that will be trying to pitch itself off the plate - make sure it is restrained. Personally, I find the lack of ceiling restraint concerning - unless that is designed in.

Do check the Velux, or Fakro, or whatever, is a suitable model for 15 degrees and that you have considered how it is opened - top hung or centre pivot, plus the minimum pitch for each.