Using a 260mm cavity lintel over a 300mm wall space

That's nonsense. What he means is "It's not something I can be bothered with"

Next time I submit some plans, instead of specifying a suitable lintel, I'll just write "Throw any old crap in" and see if the plans get approved.

 

Yes i got that feeling when I spoke to the inspector.

In regards to the actual builder I can tell you he's a very reputable builder.

he has done many builds in and around the area and have never heard of a complaint from anybody.

What he actually said is that he accepts the lintels are a little shorter width wise about 20 mm each side but there is enough overhang to be able to accommodate the weight of the three courses above and does not believe at all that it will droop down or sag.

He he said most manufacturers allow a certain degree in terms of how short you can be and this is the absolute maximum 40mm short, anything more he would not have used them. 20 mm short each side is fine. 300mm wall and the lintel is 260mm.

I asked him whether he purchased these because they were cheaper than anything else and he simply answered have I done that with anything else which he is referring to the other materials that has bought band to be fair they are good quality materials that he has been buying, from the local builders yard, who are probably the most popular yard in the town.

in any case I put it to him that there's a possibility because the lintel isn't wide enough that it might sag overtime and his response was that there's not enough weight to do that and that there is only 3 course brick and one block ontop along the wall where the three lintels have been fixed.

he has also promised that if at any time I see any cracks or sagging he's happy to come back and rectify the problem and he's only making this promise because he knows he will never have to come back to do this.

 

How many of those other customers have checked the lintels? Or checked anything?

I see a lot of shoddy builders and the same builders have been doing the same stuff for years, decades. So that does not imply they are reputable or doing things right. I even get clueless builders tendering for work and despite them having a written specification which they have priced against, they then attempt to say that the specification is wrong and the component they have fitted (yes including lintels) is correct and even better than the one they have been told to use - or required to use by British Standards. But they don't tend to want to charge less for their shortcuts and insight.

If left, the problem is that if something does go wrong, you may well get the "Sorry luv, the guarantee is up" or "Nah that's nothing to do with the lintels" reply. That's if you get a reply or the bloke is still trading (or trading under the same name or as a new company with no liabilities for past work).

Bottom line, the lintel is wrong. You either accept it or reject it. The wise thing to if you can't decide is get an independent assessment of the lintel (or wider work) and you both agree to abide by the findings - and all this at the builder's cost as he has created the situation in the first place.

 

Excellent point's. Im going to have to have another word with him

 

Hi all,

after speaking to my builder again who insisted again that there are no issues and that he's done this many times without any problems and insisting that you can have a overhang that is 20mm short each side.

I explained to him that he has to be covering the whole brick and block each side and he asked me doing the manufacturer which I just have and come off the phone to and they confirmed the same thing.

In actual fact the manufacturer said you can even use a 250 mm cavity wall lintel over 300mm width space

Meaning the minimum can be 25mm each side.

So confirmed that I can use these lintels without an issue

 

Ring the Tech department at Catnic and ask them. Why buy the wrong size to start with.

 

So you have phoned the manufacturer and they have confirmed that the 260mm deep lintel used in your extension can be used in a 300mm thick wall with 100mm wide cavity? That is good to know.

 

We don't bother with fancy lintels round here, inner skin has a lump of 8x2 and the outer just has a soldier course built off the uPVC window frame - it soon stops sagging when it settles on the glass.

 

All lintels and beams will deflect under load; the issue in this case is whether or not the deflection will be noticeable.

 

Get it in writing

 

Yes. They transferred me to the technical department. and I explained to him exactly what situation was that we have a 300mm wide wall with 100 space cavity in the middle. And that the lintel in total was 260mm wide and he confirmed that is fine to use and that either side it is only 20 mm short and that the lintels are designed to be 25 mm short each side.

And stated that it's fine to use.

 

For sure but by how much is acceptable is the question .....

 

Presumably if it's noticeable to the average man in the street, it's excessive. Similarly if the roof is under heavy snow load, and the lintels bend to an extent that the bifolds stick, then that's excessive also.
There's no hard-and-fast rule; deflection is a 'serviceability' issue rather than a structural problem.

 

My daughter worked in a Tech department for a company and had a bit of training for the job, but she used to make it up half the time if she didn't know the answer.

 

Thankyou all for your advise and assistance

 

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