What's holding up my wall?

[larry]

Happy New Year everybody,

 

I wonder if I could please call on some advice and opinions from the many wise minds on here.

 

So we have had a problem with penetrating damp. Solid walls, cement render. So I have hacked off some of the render (well, quite a lot of the render!) and that has solved the damp problem. Hurrah. 

 

Of course, one issue is that all the bricks are spalled... and I need to put back some kind of breathable render on the top... but my main question is about my lintel, I don't understand it.

 

So I have an arch, with concrete infill underneath - I'd always presumed a steel lintel was in there as well, but I actually have no idea. 

 

The concern is that the lintel has cracked in the middle, I gather/presume from replacement of original frames with uPVC windows. But the uPVC windows have been there a long time and the wall hasn't fallen down.  You can see the vertical cracking either side of the frame and there was historically on the inside evidence of a vertical crack underneath the middle of the window. We filled that in several years ago and it's not reappeared, so I am working on the assumption that it hasn't moved/cracked any further. 

 

The crack is at least 45mm deep having poked a bit of earth wire in it. Extends perhaps 3mm across at widest point. 

 

It's a gable end wall, but the 1st floor joists are sitting on this wall so it is taking some weight.

 

Above the first floor window there's also looks evidence of an arch but the lintel is timber, and, from having looked at this from the inside of the house (when putting up woodfibre boards) in good condition.    

 

It's a 1920s house. Dwarf cavity walls with solid walls on top. 

 

Have people come across this sort of lintel arrangement before?  And do I just ignore it or should I get some work done to strengthen it? I've had one company indicate they could reinforce with helical bars which sounds great but I've got no experience of this. 

Any easy way to work out if there is a steel in there without hacking back the concrete? (I've tried poking a tiny magnet in to see if it magically got picked up - no dice)

 

I'll ask a question about render separately...

 

[PeterW]

Just looks like mortar infil to me - the arch is doing all the work there by the looks of it. 
 

If you’re handy with a grinder and have a decent scaffold to work from then you could helibar it yourself using one of the kits - it’s basically 30mm deep cuts with 6mm twist bars and then epoxy grout inserted into the cracks. That will stop it moving any more and you can always drill and inject epoxy mortar into the crack too.

[larry]

59 minutes ago, PeterW said:

Just looks like mortar infil to me - the arch is doing all the work there by the looks of it. 
 

If you’re handy with a grinder and have a decent scaffold to work from then you could helibar it yourself using one of the kits - it’s basically 30mm deep cuts with 6mm twist bars and then epoxy grout inserted into the cracks. That will stop it moving any more and you can always drill and inject epoxy mortar into the crack too.

 

Thanks so much Peter - that's really helpful though I'm not sure I'm quite that brave!!  But it's good to know it's not a mad idea in general. 

[Adsibob]

I discovered something similar after we removed the pebbledash from our 1930s semi in preparation for upgrading the thickness of the wall with insulation and render (part of the pebbledash was also damp):

if you zoom in, you will see there is cracking above the wooden (!) lintel. My SE recommended we use helifix to stitch the cracked bricks together. In your case, maybe you can do something similar.

[larry]

2 minutes ago, Adsibob said:

I discovered something similar after we removed the pebbledash from our 1930s semi in preparation for upgrading the thickness of the wall with insulation and render (part of the pebbledash was also damp):

if you zoom in, you will see there is cracking above the wooden (!) lintel. My SE recommended we use helifix to stitch the cracked bricks together. In your case, maybe you can do something similar.

 

Well, at least the wooden lintel made it easy to fix curtain poles?!!

 

Goodness, yours does look very similar indeed.  Similar windows too!!

 

Did you go for the Helifix in the end? And what did you end up doing to the rest of the wall?

[Adsibob]

Just found an email from the SE when he commented on my crack. He said this:

 

Removing the render you will unfortunately unvail numerous cracks especially when you replace the windows.

What you have found is an excellent example of a brick relieving arch below. Where you have a timber beam / lintel with a brick arch built into the wall above the ground floor window.

The movement is negligible as although there is a crack the coursing has still remained aligned.

I would recommend the crack is stitched with helifix helibars. With the crack grouted not resin infilled. Can you check to see if it runs internally as well. [I checked and it didn't]

The brick arch I would just leave well alone unless on removal of the windows the timber lintel settles as then we would need to provide another means of remediation whilst the windows are out.

 

 

We did the helifix helibar stitching to the bricks and then grouted as recommended by the SE.

 

For the wall upgrade we had to tackle damp under the ground floor window. A RICS surveyor designed a solution for us with assistance from the Dupont technical dept. This is basically what we did:

 

It allowed the wall to dry from the inside, whilst staying impermeable to the elements on the outside. Outside was:

• covered in Kingspan Kooltherm K7 (we did about 45mm thick of K7, but do 60mm or 70mm if it doesn't ruin your architectural details that are original to the house - a lot of people here will tell you to do much more, but they are new-builders, us renovators have to accept that ruining the look of the original house with a bit of extra insulation isn't worth it)
• then a mesh was put up
• that was rendered first with cement, i believe - this was the hardest part, the tradesman was a real artisan though and did a great job
• then one of these finish coats from Ceresit (https://www.ceresit.com/en/products/facade-solutions/facade-finishes.html), though I can't remember which one we went for. I have left over in the shed if you want me to check.

It looks bloody brilliant.

 

EDIT: I should add that it is worth consulting a professional on what to do, because every house structure and situation is slightly different and in our case, because of the damp and the need to waterproof whilst allowing the inside to breathe, we had some complexities. But Dupont did an interstitial condensation risk analysis for me (for "free"), which my RICS surveyor checked, and this together with the fact that my RICS surveyor is very good gave me confidence the system would be fit for purpose.

Edited January 4, 2023 by Adsibob

[George]

A shallow arch like that is unlikely to be the main load bearing element - as in the SE's email, much more likely to be a relieving arch. That is, a shallow arch working in combination with a beam below. The beam can be made smaller thanks to the arch distributing the load away from the centre of the beam.

 

The infill appears to be mortar. I would chip a bit away and see if there is a beam still there. The mortar may have led to timber rot, or some other remediation work was done in the past already.

 

Crack stitching I agree with - on jobs I default to 'manufacturer's recommendations' but I have had some success on my own buildings with bedding the stainless steel rods in lime mortar. I figure it doesn't create such a hard spot and is more akin to new-build bed joint reinforcement rather than using the 100% rigidity of the resin. However... this would be 'at risk' and I hope one day helifix will do research on this approach.

 

 

You should definitely put up external wall insulation as part of the re-render. 

[larry]

10 hours ago, Adsibob said:

Just found an email from the SE when he commented on my crack. He said this:

 

Removing the render you will unfortunately unvail numerous cracks especially when you replace the windows.

What you have found is an excellent example of a brick relieving arch below. Where you have a timber beam / lintel with a brick arch built into the wall above the ground floor window.

The movement is negligible as although there is a crack the coursing has still remained aligned.

I would recommend the crack is stitched with helifix helibars. With the crack grouted not resin infilled. Can you check to see if it runs internally as well. [I checked and it didn't]

The brick arch I would just leave well alone unless on removal of the windows the timber lintel settles as then we would need to provide another means of remediation whilst the windows are out.

 

 

We did the helifix helibar stitching to the bricks and then grouted as recommended by the SE.

 

For the wall upgrade we had to tackle damp under the ground floor window. A RICS surveyor designed a solution for us with assistance from the Dupont technical dept. This is basically what we did:

 

It allowed the wall to dry from the inside, whilst staying impermeable to the elements on the outside. Outside was:

• covered in Kingspan Kooltherm K7 (we did about 45mm thick of K7, but do 60mm or 70mm if it doesn't ruin your architectural details that are original to the house - a lot of people here will tell you to do much more, but they are new-builders, us renovators have to accept that ruining the look of the original house with a bit of extra insulation isn't worth it)
• then a mesh was put up
• that was rendered first with cement, i believe - this was the hardest part, the tradesman was a real artisan though and did a great job
• then one of these finish coats from Ceresit (https://www.ceresit.com/en/products/facade-solutions/facade-finishes.html), though I can't remember which one we went for. I have left over in the shed if you want me to check.

It looks bloody brilliant.

 

EDIT: I should add that it is worth consulting a professional on what to do, because every house structure and situation is slightly different and in our case, because of the damp and the need to waterproof whilst allowing the inside to breathe, we had some complexities. But Dupont did an interstitial condensation risk analysis for me (for "free"), which my RICS surveyor checked, and this together with the fact that my RICS surveyor is very good gave me confidence the system would be fit for purpose.

 

This is just so useful - thanks so much for sharing. To be honest I'd sort of mentally written off EWI - partly as we have already started IWI (the top half is done with Woood Fibre), but also practically I worry it would be a tricky (expensive) job - would need to add a new line of roof tiles to the gable end that has , and move two toilet stacks - one cast iron - and a drain that abut the house. Plus the dwarf cavity walls mean a 50mm protrousion from the house already about 80cm up the wall. Maybe this is just par for the course and to be fair I haven't had any quotes in to look at this - which I should probably do. 

 

[larry]

21 minutes ago, George said:

A shallow arch like that is unlikely to be the main load bearing element - as in the SE's email, much more likely to be a relieving arch. That is, a shallow arch working in combination with a beam below. The beam can be made smaller thanks to the arch distributing the load away from the centre of the beam.

 

The infill appears to be mortar. I would chip a bit away and see if there is a beam still there. The mortar may have led to timber rot, or some other remediation work was done in the past already.

 

Crack stitching I agree with - on jobs I default to 'manufacturer's recommendations' but I have had some success on my own buildings with bedding the stainless steel rods in lime mortar. I figure it doesn't create such a hard spot and is more akin to new-build bed joint reinforcement rather than using the 100% rigidity of the resin. However... this would be 'at risk' and I hope one day helifix will do research on this approach.

 

 

You should definitely put up external wall insulation as part of the re-render. 

George- thank you so much. I wasn't aware of a potential risk about using helifix with lime mortar but I'm glad that even though you've introduced this you think it could work!  

 

Re the infill - it's a LOT harder than the mortar used around the bricks, and to me seems similar to the Quoins that I've uncovered around the edges of the wall. 

 

Sounds like though the key thing is to work out whether there is a anything within the infill or not given the views so far. I have to say I'm a little bit worried to go at this heavy with an SDS drill to try to find out but maybe I need to drill a few holes this weekend and see what I hit...

[George]

Although it's not a close up, it looks like trowel marks in the infill, which would suggest it's mortar. A 3:! mix can be nearly as strong as stone!

 

I'd get a masonry hammer (wear safety glasses) to chip away rather than an SDS.

[larry]

Just to update/bring this full circle. I managed to find a local builder who uses "Thor" Helical bars and they have (I hope) sorted this with two long helical bars above the whole window and eight separate bits coming up through the arch. Felt I'd reached the limit of what I was comfortable doing myself and pleased/reassured we've had it done. Next job working out what we put on top. Hugely appreciate the advice on here.