Possibly a bonkers idea - cavity wall insulation

[cojmh]

Well, the fun and games are due to start this week.

It took a long time to get everything sorted with the structural engineer which kind of brought the whole project to halt for nearly 6 weeks. But we have got there now and both the structural engineer and building control are happy with the plan.

We have investigated all of the foundations along the whole gable wall end and 50% of it already had sufficient foundations for the move. So we only needed to extend half of the foundations thankfully. All of the foundations are now project out between 300mm and 380mm from the existing wall (we are only moving the wall by a maximum of 40-50mm).

The supporting steels will arrive on Monday and the brick work will start coming down on Wednesday. The gable wall end will be taken down and rebuilt in 7 sections and the builder is hoping it will take 2 weeks to do.

the butterflies will arrive soon I am sure!

[cojmh]

Thought I would post an update.

Just read my last message with the comment "The gable wall end will be taken down and rebuilt in 7 sections and the builder is hoping it will take 2 weeks to do." and well .... it took a bit longer!!

We are currently taking down section 7 ready to be rebuilt next week ..... so I am hoping by next Friday it will mean that the scaffolding can come down and we will be switching back to ground level (or below - Drain pipes and gas mains etc.). In the end it will have taken closer to 5 weeks!

Found quite a few gremlins under the surface - so it has been a worthwhile process to deal with those.

I will sort out all my photos and upload a few if people are interested?

[Fintray]

Thought I would post an update.

Just read my last message with the comment "The gable wall end will be taken down and rebuilt in 7 sections and the builder is hoping it will take 2 weeks to do." and well .... it took a bit longer!!

We are currently taking down section 7 ready to be rebuilt next week ..... so I am hoping by next Friday it will mean that the scaffolding can come down and we will be switching back to ground level (or below - Drain pipes and gas mains etc.). In the end it will have taken closer to 5 weeks!

Found quite a few gremlins under the surface - so it has been a worthwhile process to deal with those.

I will sort out all my photos and upload a few if people are interested?

I'm interested in seeing the photos.

[cojmh]

Ok, I will end up posting this over a few posts with as much info as I can- in case anyone else is crazy like me.

After much discussion with building control and subsequently a structural engineer - we had to do a lot of investigating.

We visually checked the foundation top and sides along the whole gable wall end so that we knew exactly what was there. Turns out the foundations were between 850mm and 900mm deep and extended out from the brick/blockwork by between 130mm and 150mm.

Building control specified that they wanted 150mm projecting from the proposed new outer course of bricks. Our structural engineer wanted a lot more - but probably for different reasons.

As we needed to increase the cavity by 50mm this would mean 80mm projection at the narrowest place.

So we were told to stitch an additional 200mm of concrete on to the existing foundation. Luckily for us we found that that this was only needed for about 50% of the foundations.



To do this my builder created the necessary space (which was a lot more than 200mm as we had to get a drill in to make horizontal holes) and we put in 16mm diameter rebar into the existing foundations. The specification was that the rebar had to be:

• Horizontal

• 150mm embedded into the existing foundations

• Projecting 100mm into the new concrete

• placed in two horizontal rows, the first row 100mm from the bottom of the existing foundations and the second row 100mm down from the top of the foundations

• Rebar was placed at 300 centres with resin bonding

Once this was done we were ready to take down the wall in sections.

More posts to follow

[spread-tee]

Blimey that brings back memories, I see the disconnected hep sleeve standing at the ready, does that mean your builder is paddling around in a trench full of sewage?? It always seems very daunting at the start but it will all be worthwhile in the end. Keep the piccys coming and good luck.

Desp

[cojmh]

Blimey that brings back memories, I see the disconnected hep sleeve standing at the ready, does that mean your builder is paddling around in a trench full of sewage?? It always seems very daunting at the start but it will all be worthwhile in the end. Keep the piccys coming and good luck.

Desp

Thankfully not sewage ... it was standard drainage from gutters and run off only. However the problem we do have is that the water table around here is very high (apparently before this area was built up it was almost like marshland) and as a result 1m down water is always coming in. Had to invest in a pump so that we could clear it every day.

[Joeboy]

Ok, I will end up posting this over a few posts with as much info as I can- in case anyone else is crazy like me.

After much discussion with building control and subsequently a structural engineer - we had to do a lot of investigating.

We visually checked the foundation top and sides along the whole gable wall end so that we knew exactly what was there. Turns out the foundations were between 850mm and 900mm deep and extended out from the brick/blockwork by between 130mm and 150mm.

Building control specified that they wanted 150mm projecting from the proposed new outer course of bricks. Our structural engineer wanted a lot more - but probably for different reasons.

As we needed to increase the cavity by 50mm this would mean 80mm projection at the narrowest place.

So we were told to stitch an additional 200mm of concrete on to the existing foundation. Luckily for us we found that that this was only needed for about 50% of the foundations.



To do this my builder created the necessary space (which was a lot more than 200mm as we had to get a drill in to make horizontal holes) and we put in 16mm diameter rebar into the existing foundations. The specification was that the rebar had to be:

• Horizontal

• 150mm embedded into the existing foundations

• Projecting 100mm into the new concrete

• placed in two horizontal rows, the first row 100mm from the bottom of the existing foundations and the second row 100mm down from the top of the foundations

• Rebar was placed at 300 centres with resin bonding

Once this was done we were ready to take down the wall in sections.

More posts to follow

Deeply impressed! The new insulated wall is going nowhere.

[cojmh]

The structural engineer came up with a plan for taking down the wall in sections. I think they were being super cautious both to cover themselves and also because my builder is quite young and has not done a wall take down on this scale before.





Couple of updates to this diagram - The top level on this diagram is to be taken down in one go (i.e. 7 & 8). Also the RHS specified initially was 200x100x10 ..... which were going to be problematic for a few reasons:

• The longest section of steel would be 3000mm long and at 10mm thick would have weighed close to 130KG .... not something we wanted to be handling at height whilst also trying to manipulate acrows and strong boys.

• The cost was going to be prohibitive. best price I could get was circa £2K including cutting and delivery. Which to me was madness for 2 weeks use (as we thought at the time)

In the end we got 200x100x5 - which I manage to get for a much more reasonable £700 inc cutting, delivery and VAT

The method to take down one section of the wall is to remove a brick (or two) so that it is possible to get an acrow with a strong boy in. Spacing of the acrows are to be 500mm apart.




Once the initial acrows are in we can then remove 3 courses of brickwork (the space required to be able to get the steels up and in)




Once we have the space we can get the steel in .... with some wood plank cut to fit between the first set of acrows so that we can get the first set of acrows out again. Acrows under the steel are again spaced out by 500mm.




Once in we can take down the brickwork




We found it took quite a while extra to do all of these steps .... but having done this a few times on the house it was rock solid .... no movement and we have had some pretty bad weather at times (wind and driving rain) but everything held together.

More to follow .....

[Richard77]

Hope everything goes well mate... Will be keeping a keen eye on this thread to see how it goes due to my own gable issues!

House had quite a bit of movement in the 90's and had some remedial work done on it. A bit of underpinning, etc.

We bought it in 2015 and it had quite significant bulging on the gable wall and several places of cracking. It hasn't gotten any worse since the 90's apparently and structural engineer said it is historical movement.

We got the whole of the house externally piled when we bought it and had to go down approximate 8 metres to find solid ground. Done this as a precaution. We have seen no difference in the wall(s) for the 9 years we have owned it, so it seems ok (fingers crossed).

We are a looking to get rid of the bulging brickwork though as it is quite an eye sore. I don't know whether it's the subsidence or wall tie failure or both. It isn't getting any worse though so that's a good sign. It is a bit daunting when thinking about knocking down some or all the wall and rebuilding. I am a bit wary to get anything done to it in case the worst happens and it all falls down like a pack of cards!

[spread-tee]

Forgive me for the silly question, but why start dismantling the wall from the bottom? I did something similar a while back on a smaller scale to be fair and we took it all down from the top, no propping needed. I take it your house is standard construction, IE the inner leaf is the load bearing element. Does he want you to re-build it from the top down?? High water table is a right pain in the arse , don't tell me you are on clay too? Heavy shit!

Desp