External render blown/damp/issues, best solution?

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.

Oh and I think I'd be under 25% if I just patched the bad bits. But if the whole wall needed re doing then I wouldn't. Then you have to improve the insulation right? So would external wall insulation be the best bet? Is it ok to do on these Victorian houses.  As far as I know it is a double layer of bricks with a gap in the middle

Or I read elsewhere that for these houses you should use a lime render. It's all quite confusing

stuart45

If it's a cavity wall there are other alternatives for insulation.  Penetrating damp should be less likely than with a solid wall as long as the cavity is clear. You could be OK with the existing render if it's a cavity wall.

delmonta

stuart45 said:

If it's a cavity wall there are other alternatives for insulation.  Penetrating damp should be less likely than with a solid wall as long as the cavity is clear. You could be OK with the existing render if it's a cavity wall.

When I look in the hole for the toilet waste there are two layers deep of bricks, but the gap between is minimal. 

Looking in the kitchen waste hole, I see a slightly larger cavity in the middle,

Is it a cavity wall if it's two layers of bricks? Regardless of the size of the cavity? 

stuart45

Needs to be 2-3 inches to be a proper cavity. Some solid walls are built in Stretcher bond, and look like a cavity wall, but the cavity is only about 3/8 to 1/2 or so isn't really a cavity wall. There will always be a small gap with a stretcher bond 9 inch wall, but it's needs to be at least 2 inches to be a cavity wall.

delmonta

stuart45 said:

Needs to be 2-3 inches to be a proper cavity. Some solid walls are built in Stretcher bond, and look like a cavity wall, but the cavity is only about 3/8 to 1/2 or so isn't really a cavity wall. There will always be a small gap with a stretcher bond 9 inch wall, but it's needs to be at least 2 inches to be a cavity wall.

Ok thanks, that's a shame, looks like mine is under an inch

stuart45

That's really a solid wall built in Stretcher bond then. The bricklayers make the cavity (known as the wall joint in a solid wall) a bit bigger than the standard 3/8inch to make it easier to get their fingers into the gap when laying the inside brickwork. As the inside is plastered it does not matter like on a garden wall with 2 face sides. In theory the wall joint should be filled with mortar, but as this can cause the brickwork to belly out sometimes a lot of people  don't bother. 
However leaving voids in a solid wall can cause damp issues.

FreeBear

Damp at the rear, bottom left ?

I'd be looking at the brick wall that forms your boundary. It could be that it doesn't have a DPC and is bridging the one in the house.

As for solid or suspended timber - Doesn't appear to be any air bricks on other properties in the area. Not that they are too easy to spot from streetview. A typical air brick looks something like this -

delmonta

stuart45 said:

That's really a solid wall built in Stretcher bond then. The bricklayers make the cavity (known as the wall joint in a solid wall) a bit bigger than the standard 3/8inch to make it easier to get their fingers into the gap when laying the inside brickwork. As the inside is plastered it does not matter like on a garden wall with 2 face sides. In theory the wall joint should be filled with mortar, but as this can cause the brickwork to belly out sometimes a lot of people  don't bother. 
However leaving voids in a solid wall can cause damp issues.

Ok that seems to be the case. So in my situation would you say a lime render might be preferable? 

delmonta

FreeBear said:

Damp at the rear, bottom left ?

I'd be looking at the brick wall that forms your boundary. It could be that it doesn't have a DPC and is bridging the one in the house.

As for solid or suspended timber - Doesn't appear to be any air bricks on other properties in the area. Not that they are too easy to spot from streetview. A typical air brick looks something like this -

Yeah bottom left. Thats an interesting thought, so should an external wall have DPC at the bottom?  How would I know if it was causing the damp issue. To be honest I could knock that wall down, its not doing anything apart from taking up space. Although I quite like the bricks! 

No I havent seen any of those air bricks. Is there something else I should be doing considering I dont have these?

Thanks for all the help, very useful

stuart45

delmonta said:

stuart45 said:

That's really a solid wall built in Stretcher bond then. The bricklayers make the cavity (known as the wall joint in a solid wall) a bit bigger than the standard 3/8inch to make it easier to get their fingers into the gap when laying the inside brickwork. As the inside is plastered it does not matter like on a garden wall with 2 face sides. In theory the wall joint should be filled with mortar, but as this can cause the brickwork to belly out sometimes a lot of people  don't bother. 
However leaving voids in a solid wall can cause damp issues.

Ok that seems to be the case. So in my situation would you say a lime render might be preferable? 

Lime  would be better, but it does mean hacking all the cement off.