External render blown/damp/issues, best solution?

delmonta

Hi, the back of my house is a bit of a mess. I started chipping off a patch of blown render and more and more came off. I've taken it back as far as I can and it feels very solidly adhered in the places that are left, almost impossible to get any off with a claw hammer or chisel etc. 

The bottom left section was extremely thin render, almost like a tiny layer of sand then paint. And I was able to just scrape back that patch with a scraper, and its very damp underneath. I also had some damp issues in this corner internally. Could this just be that the render/paint had worn so thin that water got in to the wall? If so, how would I remedy this now considering its been left for many years this way. I feel stupid for not doing anything but I was renting it for years and out of the country. 

I spoke to some renderers, one said you could just scrape back to whats solid and then patch it up and paint, cheapest solution. Others said the render is too old, you need to get it all off. But it's nearly impossible to get the solid bits off! Also, these guys didn't know about the damp bottom left corner. 

One of them said the best possible thing would be to get External Wall Insulation (EWI), but this is very costly. They said this could be done over the current wall once the hollow/blown bits are chipped off. 

The only other thing, is that in the second picture if I knock on that area the wall sounds a hollow. This worries me, what can you do about that? 

Sorry for all the questions, but I'm already on borrowed money and time! Any advice would be great, what would be some of my best options. Also, is it really bad to leave the wall exposed as it is? Should I be looking to cover the areas I chipped the render away somehow, if so how!? 

thanks

stator

Is your house Crosswall construction ? AKA Rationalised Traditional Construction?

If you're not sure post some photos of the houses on your street that same as yours

Ectophile

Looking at that second picture, I can't help thinking that you have render on top of render.  It was quite fashionable at one time to make mock stone walls by rendering them and then scoring the render to look like the joins between stone blocks.

If that's the case, the original render may have blown as well.  There are obvious cracks in it the would let water in.

delmonta

stator said:

Is your house Crosswall construction ? AKA Rationalised Traditional Construction?

If you're not sure post some photos of the houses on your street that same as yours

Sorry I dont know what that is! But if you went on google street view, its Warminster Road, Bristol, BS29UH

I'll attach some images I grabbed from that....

delmonta

Ectophile said:

Looking at that second picture, I can't help thinking that you have render on top of render.  It was quite fashionable at one time to make mock stone walls by rendering them and then scoring the render to look like the joins between stone blocks.

If that's the case, the original render may have blown as well.  There are obvious cracks in it the would let water in.

Interesting, I thought it looked weird and I'm sure it was bricks. I will chip a bit off tomorrow and see if I can find out. 

If this is the case, then I guess just take back the hollow bits a bit further and re render? In a way this would be better as I thought maybe blocks would be falling apart, but if its just render then that could be better

Any thoughts on the rest? The very damp section, or the best solution for fixing it all

stuart45

I would say that's render with Ashlar markings. Problem with cement render is that when cracked it allows water in, then traps it in the wall. Lime render tends to perform better.

It's not Cross wall construction. That was really popular in the 60's. The weight of the floors and roof is taken on the party and gable wall which allows for windows along most of the front and rear flanks.

delmonta

stuart45 said:

I would say that's render with Ashlar markings. Problem with cement render is that when cracked it allows water in, then traps it in the wall. Lime render tends to perform better.

It's not Cross wall construction. That was really popular in the 60's. The weight of the floors and roof is taken on the party and gable wall which allows for windows along most of the front and rear flanks.

Ok thanks, thats interesting. Do you have any advice for the best way to remedy my poor old wall! 

stuart45

Depends on how much time and money you have. If you try and get the really hard stuff off you might you might damage the brickwork. Ideally it's best to get off any cement render and use a lime render.

delmonta

stuart45 said:

Depends on how much time and money you have. If you try and get the really hard stuff off you might you might damage the brickwork. Ideally it's best to get off any cement render and use a lime render.

Thanks, I am already on borrowed money, but I have a lot of time! I was hoping to patch it up as cheap as possible to last a year or two and then hopefully get external wall insulation done. 

FreeBear

delmonta said:  I am already on borrowed money, but I have a lot of time! I was hoping to patch it up as cheap as possible to last a year or two and then hopefully get external wall insulation done. 

Judging by the other properties along your road, they appear to be Victorian era with solid brick walls. A cement based render (including stuff like K-Rend) would be the last thing you'd want to slap on. Removing more than 25% of the render would trigger building regs and the requirement to insulate (although, there are get out clauses). Fitting EWI needs great attention paid to the detailing and the right materials used. It would also mean the loss of a lot of the character details such as the stone work around the windows and the moldings just under the roof line - Both worth preserving in my opinion..

If the Ashlar finish is cement based, then it will be exacerbating any problems with damp and would best be removed. It would also give you opportunity to check that lintels have been fitted over the window & door at the back. There doesn't appear to be any air bricks at the back, so unless you have solid concrete floors, some should be fitted.

delmonta

FreeBear said:

delmonta said:  I am already on borrowed money, but I have a lot of time! I was hoping to patch it up as cheap as possible to last a year or two and then hopefully get external wall insulation done. 

Judging by the other properties along your road, they appear to be Victorian era with solid brick walls. A cement based render (including stuff like K-Rend) would be the last thing you'd want to slap on. Removing more than 25% of the render would trigger building regs and the requirement to insulate (although, there are get out clauses). Fitting EWI needs great attention paid to the detailing and the right materials used. It would also mean the loss of a lot of the character details such as the stone work around the windows and the moldings just under the roof line - Both worth preserving in my opinion..

If the Ashlar finish is cement based, then it will be exacerbating any problems with damp and would best be removed. It would also give you opportunity to check that lintels have been fitted over the window & door at the back. There doesn't appear to be any air bricks at the back, so unless you have solid concrete floors, some should be fitted.

Thanks for all the advice. You were right, they aren't blocks it's just render with scratches in! It all feels very solid apart from one ring area and it doesn't come off easily at all in that area. 

Is this the stuff you are saying will not help the damp? The damp is really only in the bottom left and it could just be that the render was so worn. 

As for the details, the front of the house is fine and that's where all the nice details are. The back has none of that. 

Sorry what are air bricks and where should they be? The kitchen floor is concrete underneath everything