Lintel issues?

[Lintel Woes]

We are having an existing outbuilding rebuilt as the old one was falling down. There are 3 window openings and a sliding door opening. The window openings are 610mm, 1210mm and 1610mm wide, with the door opening at 2810mm.

 

The builder has brought the catnic lintels (for 100m cavity walls) to site and they are 900mm, 1400mm, 1800mm and 3000mm wide. He's installed the 1400 one above the 1210mm opening, and has partially installed the 3m one above the main door. My concerns are:

 

These lintels (except for the 900mm) do not give a bearing size of 150 either side. I thought openings below 1200 could be 100mm but not above 1200. Also catnic specify 150mm bearing widths? I'm especially worried about the one for 2.8m wide doors where the opening width should be 2810mm. He's only made the width 1790mm and when quizzed he said he would open it up when the rest of the build was done before installing the door. The lintel seems to have a bearing width of 105mm on one side and 100mm on the other - and it is this side he plans to cut out 20mm to increase the opening width to 2810mm.

 

The walls are block work with 100mm cavity. I noticed today that on Thursday he had built three courses of blocks above the lintel on inside wall only, and despite having props on site has not bothered to support the lintel. On the outside wall there are no blocks above the lintel over the bearing pads which has caused the lintel to lift clean off the pads on the outer wall side. I could slide a slate through the gap. Also the blockwork on the inside wall above the lintel has cracked along the pointing and the lintel is 8mm lower to the floor in the centre than at the edges.

 

What should we say to the builder when we see him next?

[Russell griffiths]

Time to part company. 

[Dave Jones]

Lintels upto 1.2m only need 100mm bearing, over that its 150.

 

https://nhbc-standards.co.uk/6-superstructure-excluding-roofs/6-1-external-masonry-walls/6-1-12-lintels/

 

It's a warranty fail for NHBC so i would have them removed and correct sizes. Also I'd want the door to be a HD lintel (taller).

 

Also make sure the builder puts a tray and weep vents on every lintle.

 

 

Edited September 3, 2023 by Dave Jones

[Lintel Woes]

Thanks for confirming my suspicions Dave. 
 

The lintel above the door has 3 courses of blocks and then is to have a traditional vaulted ceiling roof with slate finish. Not sure if that has any influence on the spec of the lintel? 
 

He has put some damp course barrier into the wall above the lintel which to me seems a little short to set under a block and asked what colour wall weeps we wanted when here on Thursday.

 

we were quoted 24800 for the knockdown and rebuild build which included digging out the old floor and replacing the footings with a raft with a ground beam and mesh reinforcment rather foolishly agreed to giving him 55% deposit and he got 3300 after the concrete pour. 
 

We are in an awkward spot as don’t have enough money left to complete the build if he walks off the job. 
 

They are a polite bunch when on site but impossible to contact when they are not here, texts calls unanswered etc.

 

I fear this is a harsh lesson to learn but we need to try and work with them to get this done rather than kicking them off the job.

[Dave Jones]

it may be the odd sizes weren't in stock. As its an outbuilding rules could be more lax. 

 

As long as the trays above the lintels are sorted i don't think id be over worried. 

 

Post some pictures.

[Lintel Woes]

[Lintel Woes]

[Dave Jones]

it doesnt look to bad really, they are on top of the trays. 

 

Good to keep an eye out but looks tidy job. Much worse can be found on here.

 

Do you have building control monitoring ?

[Lintel Woes]

Ashamed to say no, it’s replacing a wooden conservatory that was falling down.  It will serve as a garden room with existing UPVC doors to main house remaining. 
 

just concerned about weight of roof that’s all, we will be spending a lot of time in there as a playroom for our 1year old.

[MortarThePoint]

Are you going with a duo pitch roof with the gable furthest from the existing house?

 

What is the distance from the door to the back wall, with the barrow by it?

 

Did you happen to see a code on the Catnic as to which type it is?

Edited September 3, 2023 by MortarThePoint

[MortarThePoint]

3 hours ago, Lintel Woes said:

Ashamed to say no, it’s replacing a wooden conservatory that was falling down.  It will serve as a garden room with existing UPVC doors to main house remaining. 
 

just concerned about weight of roof that’s all, we will be spending a lot of time in there as a playroom for our 1year old.

 

Sometimes the BCO plays a convenient role of bad cop and allows the client to play good cop and not strain the relationship between the client and builder with the client still getting what they want.

 

What type of doors are to go in the 2810 opening?

Edited September 3, 2023 by MortarThePoint

[Lintel Woes]

Thanks for the replies I will get the measurements tomorrow and answer your questions. The door is a upvc slider with fixed panels ether side.

[MortarThePoint]

22 minutes ago, Lintel Woes said:

Thanks for the replies I will get the measurements tomorrow and answer your questions. The door is a upvc slider with fixed panels ether side.

 

A rough dimension would be useful. I wanted to get a feeling for the load on the door lintel.

 

Sliders can be pretty unforgiving of lintel sag I think I've heard.

[Lintel Woes]

The external dimensions are 4300 x 3200 and yes the roof will be a dual pitch I.e ridge at the top in the centre. They are putting an I-beam steel in for the ridge.  The lintel code is covered up but appears to be 1 block high roughly  210mm and 290mm wide. Ridge height is approx 4300mm

 

[MortarThePoint]

Interesting, I guess you're having a vaulted ceiling hence the ridge steel. That helps lighten the load in the lintel. On plan, the lintel needs to support 0.8m2 of roof per m plus eave overhang. That might be 1.2m2 per m. I think slate is about 35kg/m2, so that's about 50kg/m2 on plan. Perhaps total roof load on lintel is 90kg/m then add snow etc -> conservative 180kg/m (TBC). Blockwork already on there is around 100kg/m. The bearing loads are therefore (180+100)*3 / 2 = 420kgf = 4.2kN per bearing.

 

I think the standard Catnic at 3m has a SWL of 26kN so 8.4kN is well under that, but check.

Catnic CG90/100 

 

I'm surprised by your 8mm sag. That's span over 375. It only has 3kN on at the moment which is 10% of max SWL which is likely deflection limited at span over 300 or 0.003*span which is around 10mm. So you should only be seeing about 1mm at this point.

 

Are you sure the floor you are measuring to is flat? What does a 1.8m level look like held under it. I think that if you have 8mm of centre deflection, you'd have about 3mm at each end of a 1.8mm level. That assumes a rotating bearing, otherwise it would be more I guess. Actually, would be good to get a laser level across it and then easier to tell.

 

That bearing would always bug me, but I'm a ruminator by nature. At this point, it's half a day's work to rectify. You don't want to be an open cheque book, but it might smooth it if you cover the cost of the replacement lintel (about £130 I'd guess) if he takes the extra work on the chin. The blocks can be cleaned and relaid. That feels pragmatic to me as you'd be within your rights to just say fix it to him and he pays all. These things can turn ugly, but it can 'keep them honest'. You'll have to gauge the relationship for yourself. 

Edited September 4, 2023 by MortarThePoint

[MortarThePoint]

The 1400 over 1210 isn't great but less of a worry. Get the 1800 lintel for 1610 opening swapped as not yet installed. 1800 is the top end of a CG90/100 profile before a price bump which may help explain. A 1950 should still be cheap though.

Edited September 4, 2023 by MortarThePoint

[MortarThePoint]

https://condell-ltd.com/lintels/catnic-lintels/catnic-cavity-wall-lintels/catnic-cg90100-cavity-wall-lintels

 

Minimal price difference for 1800 to 1950.

 

3300mm lintel looks more than I expected so perhaps I'm out of touch with prices.

[Lintel Woes]

Thanks for your detailed and helpful responses. He sent a labourer today to drop the blockwork and remove the lintel. I got stuck in to help as lowering the blocks from and cleaning up takes time on your own never mind removing the lintel. Labourer is one who’s been on job from day one and was fine with us, he said builder told him we had to feel safe and understood our reasoning and apologised for the oversight. We are away for a couple of days so have text a few details to the builder and we will see what happens: I will try to ring him when cameras let me know he’s on site tomorrow. Once again thanks to all who replied.

 

P.S it may be that the engineering bricks are not exactly the same height in the middle but either way I think it was doubtful that the doors would have fit in the vertical.