Bowing brickwork and concrete lintel.

[fandyman]

Hi,

I've been planning to put external door between conservatory and living room (the opening is 2.5m wide) and recently uncovered a concrete lintel with bowing brickwork. The latter is bowing downwards (see photos). I've noticed from upstairs window when looking downwards that the brickwork is cracked in a stepped pattern above the opening. The concrete lintel is approx 11cm wide by 22cm high and 226cm long. It does not show any signs of cracks etc. I've also checked the length of the bearing on each side and left side is 150cm with the right being 100cm.

Above the opening there is pipework that collects the waste water from a toilet and a shower/washing basin above into the stack next to conservatory. The piping is visibly leaking making me think this would be contributing to the brickwork bowing downwards. I would think however the main reason would be missing brick lintel.

My questions would be:
Shouldn't both sides of lintel be supported with at least 15 cm bearing each side with 2.5m long opening?
Isn't the right bearing of 10cm too short for such long concrete lintel?
Shouldn't the brickwork be supported separately with reinforced brick lintel?

Any thoughts appreciated.

 

[Dereekoo]

150 bearing for lintel is just a general standard spec for conc lintels and as long as bearing on supporting brickwork is ok 100 could suffice and in your case it has. I assume that when the conservatory was added the opening was formed by taking out the existing timber windows (which were able to support the overlying brickwork) and leaving the brickwork as self supporting. As you say the brickwork strength/connectivity has decreased overtime and has led to sagging/failure and yes it would have been prudent to install a lintel at the time. Installation of a lintel now required.

 

[George_engineer]

Shouldn't both sides of lintel be supported with at least 15 cm bearing each side with 2.5m long opening?
Isn't the right bearing of 10cm too short for such long concrete lintel?
Shouldn't the brickwork be supported separately with reinforced brick lintel?

It should but if it hasn't moved then don't worry too about it. What happens with short bearings is the masonry around the lintel tends crack rather than the lintel itself failing.

If there are signs of bearing cracking then replace along with the external leaf lintel as you'll have all the kit there ready to go.

Yes the external leaf should have had a lintel. A steel angle lintel may be more appropriate to keep the solider course.

 

[fandyman]

Thank you for your replies.

Should I expose more of the masonry around the lintel for potential cracks?

Would I need structural engineer to check the existing concrete lintel and do the calcs for the new external leaf lintel?

 

[Charlie George]

Your conservatory roof and box gutter will have to come off to install an outer lintel at the same height it is now, what is the opening height now? it may be possible? if the bow is not severe, to install lintel under the soldier course and repair brickwork above, main concern is the outer leaf, the internal at least has a lintel.

 

[fandyman]

Opening height at the concrete lintel side is 207cm.

 

[fandyman]

Should I expose more of the masonry around the lintel for potential cracks?

Would I need structural engineer to check the existing concrete lintel and do the calcs for the new external leaf lintel?

 

[Dereekoo]

Should I expose more of the masonry around the lintel for potential cracks?

Would I need structural engineer to check the existing concrete lintel and do the calcs for the new external leaf lintel?

If you haven't seen any tell tale signs of cracking in the wall before you started doing your uncovering work why would you think there are any cracks to be found now.

Why would you want a structural engineer to check an existing lintel that has not previously shown any issues to be concerned about.

Possibly SE required to do calcs for external lintel but builder in liaison with BCO should be able to sort or a reputable builder if you are not involving BC

 

[fandyman]

I have now spoken to SE and was told this is a repair work and no BC needs to be involved. I will get structural calcs for new concrete lintel in the meantime but was advised I have to support the brickwork while I am taking down the conservatory as he noticed some brickwork cracking from outside above the conservatory and suggested a panel of bricks could come down and he would not risk not supporting it.

As a result I am planning to prop up the bowed brickwork as will be demolishing the existing conservatory and boarding up the opening before the RSJ gets installed.

Would you be able to advise if I can prop it up with c16 45 x 90 treated timber as I already have that in my garage? The lowest point of brickworks is at 200cm high and the highest at about 205cm. I could cut the existing timber to size and have a board on the floor and some packing at the brickwork height.

My thinking was with the boarding up protecting from outside elements a treated timber posts for temp support should be fine but wanted to double check before I proceed.

Would that work or do I have to look at getting acrow props?

 

[cdbe]

Why do you want an rsj on the outside? That's what single leaf steel lintels are designed for.

You could prop up the outer leaf with 4x2's if you want, but you'll still need acrows and strongboys (or more 4x2's and needles) at a higher level when you get round to fitting the lintel. If it's as bad as it looks in the photo and it's going to be exposed after the world I would be assessing how much loose/dropped brickwork will need rebuilding.

 

[fandyman]

Hi, Thanks for you reply.

Sorry not RSJ - it will be a concrete lintel or indeed single leaf steel.

As for the Acrow props with strongboys at a higher level I will be getting local builders to do that and install the concrete lintel at a later stage but first want to demolish conservatory myself and for that I need to support the bowed brickwork before it kills somebody when I start to take it down.

Do you know whether I need a stronger support above this ground floor opening (currently planning on leaving the current inner concrete lintel and adding new outer concrete lintel for the brickwork support) like proper steel beam for both inner and outer walls if I ever wanted to convert my loft to a dormer with an ensuite bathroom (being 6 times stronger to concrete with metal bar inside).

Need to double check with SE for that but just wondered if anyone has experience.

 

[cdbe]

It's just twigged with me, there is currently nothing other than a bit of friction supporting that outer leaf and you should prop it urgently (with your 4x2's)- it could collapse at any time.
A concrete lintel on the outer skin won't look nice, hence they make the steel ones. A loft conversion bears on the inner skin (and generally relatively little) so the existing ground floor lintel should be perfectly adequate.