House exterior rendering repair

NeoVo · 4 Jan 2017 at 17:35

The home we bought in last 6 months has some issues with the exterior rendering.

The 3 bed detached house was built in 2001 but essentially the rendering was not maintained, cracks have appeared which has allowed water to get between the brick/block and render and has green algae growing trough the cracks. The render which covers the perimeter and all but the lower 2 foot of the property is painted white, though this is now an off white colour coated with mildew etc. Very much the ugly duckling property on our estate until we sort it!

During temperature changes (particularly current icy conditions) and sunlight on the house faces; noises can be heard which I believe is the rendering loosening off the walls, though fortunately none has actually given way. The rendering which is painted white sounds mostly hollow when tapped on it. I'm pretty confident it wouldn't take much to remove it, though would be out of my depth to sort myself in all honesty?!

During purchase we had it checked via house survey and was not deemed to be structural and this is not a concern; and this was reflected in the purchase price. The estate agent openly admitted they had quote and was in the region of £6000, though I would not be surprised if it was more than this?

I will shortly be speaking with builders and companies specialising in exterior rendering to get quotes for the remedial work but wondered if anyone could offer any advice, things to watch out for or experiences with this sort of work?

Cheers

LOAM · 4 Jan 2017 at 19:48

One thing to be mindful of is when doing work to a thermal element you may find you fall in to an opertunity to improve requirement under ADL1B. Removing 25% or more of the external render, you can be forced to improve the entire thermal envelope to bring it inline with current regs, depending on your existing wall construction this could mean the use of an external insulted render system. This may be desirable but can significantly increase the costs.

As for products, we've used silicone based through colour renders now for the last 10 years, no one uses sand cement unless you really have to. k-rend or wbs-ltd are our usual chaps, ive just used K-rend on our extension and it was excellent.

Solus · 5 Jan 2017 at 19:06

Can't you sand cement render over the cracks and then paint your house?

thezappa · 5 Jan 2017 at 22:08

Wouldn't suggest filling the gaps. To coin a phrase: that would be (almost literally) papering over the cracks and wouldn't stop the existing render coming off, if as the OP says it sounds hollow when tapped it sounds as if it has de-bonded from the wall and it's just a matter of time.
It sounds as though there has been water ingress and the freezing whether is causing the freeze/thaw action and that is the noise. If that is the case you may want to have a look elsewhere around to see if water can or has got in somewhere as that is often the reason for failure, could be around soffits, windows, doors, cable penetrations. If any junctions between the wall and the render haven't been properly sealed and you re-render you'll get the same problem.

NeoVo · 6 Jan 2017 at 01:14

Thanks for your help/guidance so far

.

A repair might have been viable during early stages of light cracks appearing but I think it's beyond that stage the previous owner (landlord who had tenants) did not do anything about it when they should've. There is a house almost identical in layout/design/render a minutes walk down the road in typical 2000 house estate style where render appears to be in perfect condition.

I believe our house has double cinder blocks with cavity walls between, just hope that insulation and thermal properties have not become damp as a result.

Was hoping maybe render could be removed and expose brickwork underneath but I have suspicions render is applied directly to cinder blocks to cut costs during house builds?

thezappa, it's interesting you mention the soffits; our home buyers survery did suggest that the first level lead flashing is lifted slightly and requires redressing; this perhaps not the cause but a contributing factor to moisture/algae building up behind the render.

Should I expect tradesman to generally provide free quotations and inspection with no obligation, what's standard practice in this sort of scenario? (first property). I'm new to this sort of thing, but don't want to be taken advantage of because of my limited knowledge!

thezappa · 6 Jan 2017 at 21:47

NeoVo said:
I believe our house has double cinder blocks with cavity walls between, just hope that insulation and thermal properties have not become damp as a result.

Was hoping maybe render could be removed and expose brickwork underneath but I have suspicions render is applied directly to cinder blocks to cut costs during house builds?

Unlikely blockwork would have been used for both walls, it's more likely brick and block as the internal wall would be lightweight concrete to provide better insulation and the external masonry wall would be load bearing of the roof.
Could be concrete just don't see it often

NeoVo said:
thezappa, it's interesting you mention the soffits; our home buyers survery did suggest that the first level lead flashing is lifted slightly and requires redressing; this perhaps not the cause but a contributing factor to moisture/algae building up behind the render.

Perfectly possible, would be worth getting it checked out, get a roofer round and ask for a price to fix it. Shouldn't need replacement but sealing any gap would be a very good idea.

NeoVo said:
Should I expect tradesman to generally provide free quotations and inspection with no obligation, what's standard practice in this sort of scenario? (first property). I'm new to this sort of thing, but don't want to be taken advantage of because of my limited knowledge!

Usually they do (offer free visits and quotes, will probably say on their website), some don't but it's pretty unusual. They ought to advise you if they do charge.
Just drop them a line or an e-mail and ask them to have a look, you already know it needs replacing so there shouldn't any surprises. Ask them to come round to have a look at render on whichever elevations you need it, perhaps give them an idea of area (m2), tell them you're pretty sure it needs taking off and doing properly and see what they say, they should quote and you can have a think about it when you get it.
Post back here if you want