External render question

[Mark S.]

The turnips that owned my house had it rendered with the usual pebble dash type stuff at some point.

However they picked the cheep option I presume because the cowboys didn't remove the previous render (original I think) so it's blown all over the place. It's worst on the rear wall.

Bits have lifted off and fallen off over the past two years but I've other things to do so I've just left it be and swept up when it falls off.

However this crappy weather has forced a big sheet off (4 x 6) at a guess which was on the floor when I went round tonight so that's now bagged up to go to the tip Saturday. History lesson over. ;-)

How important is this render in the first place?

I ask because the house isn't running with damp (ok it's "damp" a bit but there's no central heating as such). The walls aren't running with it etc.

Given that it's solid concrete construction (foot thick) what's the render actually doing?

Mark S.

[Michael Mcneil]

Your walls are 12" solid concrete?

Beats me. The first layer must have started weathering so they cowboyed it for a quick sale by the sound of it. Sounds like a few days with a Kango are looming. Then a week with a plastering float or some panelling.

[Jerry Built]

On the ground outside, I assume?

You've concrete walls! That's unusual. I expect that the render is there only there for decorative reasons.

I was going to suggest that the reason that the render is falling off is because it's harder than what's underneath, but if it's concrete that should not be the case. Perhaps the original house or render was painted with something before being rendered?

How old is this very interesting abode?

J.B.

[Mark S.]

Well a bit misleading in that they are poured concrete not "solid" like a bunker so my bad there guys, sorry. :-)

The stuff you see on TV where they fasten a load of polystyrene boxes with wire then fill them with concrete well this is a 1955 version of that idea minus the polystyrene. So the walls are as thick as the usual but with no cavity.

The stuff is like a concrete slurry mixed with pebble/ballast type material set hard.

The exterior walls have a coat of cement render that's thin then they had another coat of some seriously sandy render with chippings this was painted poo brown then at some point (long before I bought it) had another very sandy and thick render with the more usual chippings over the top.

Yes it was outside, arm down the drain tomorrow to fish the stuff out of there. :-(

No need for a kango that's for sure, I poked off the bits left on after the two falls with a stick. lol. Secure it ain't.

Only reason the back wall is so bad is the cowboy guttering next door runs the wrong way and overflows at my end.

Mark S.

[N. Thornton]

Sounds like a good opportunity to remove it all. Render increases damp more often than it reduces it, as the net flow of water is from inside out, not from outside in. Humans produce loads of water vapour every day, then theres showers etc.

The only time I'd be cautious about removing it is if the concrete wall is disintegrating, and the render is being questionably used to hold it together.

I would think it is there for decoration only.

Regards, NT

[IMM]

Only if it is not done properly.

Very true, Some of the goons here don't know that, and think that humidity can be higher outside a house than in.

The best is to install exterior foam high performing insulation. This building would need some. Some of this foam can be rendered directly. Some needs a board over for the render to be applied. Exterior insulation is a great idea as it virtually eliminates cold bridging.

[Mark S.]

The walls are no way disintegrating, Thank god for SDS coz anything else would be useless. ;-)

From what I've taken off inside and out on the walls they seem to have a top coat of a cement type "plaster" as the concrete itself is uneven due to the pebbles/agregate they are made up of.

I'll take some pics today and post a link so you can all have a nosey. :-)

Mark S.

[N. Thornton]

wrong

RH can be, and often is.

wrong, as usual. The best insulation is 2 combi boilers of course!

Regards, NT

[The Natural Philosopher]

Ive seen this type of construction a lot abroad - anything from precast concrete blocks filled with cement down the holes to actual cast on site shuittered concrete.

Its great in hot climates because of teh thermal mass.

Its normal to render it with stucco type finsishes - possibly as extra weather proofing, but more likley to just have a decorative finish.

I've seen 'cinder blocks' and celcon type blockwork done the same way - they need the render as they are porous.

Pesronally I'd strip it, re render it and paint it, and, it its truly solid, dry line it with insualation. It will be fabilously congforatble and reasonably good looking if you do.

You could re-pebble dash it if you like that finish. I hate it, but its low maintenance.

Or you could drill holes and tie a brick facing on the outside with insulation batts between.

Lots of options.

[Mark S.]

Thanks.

From the bit I've seen in the loft that's not "skimmed" it was some kind of metal mesh that was removed after pouring and setting.

I would have to agree with the thermal mass comment. It seems to stay "comfy" inside when it's cooling down in the evenings and the times I've slept over there not that cold with even minimal heating, obviously takes longer in the winter to warm the mass up but it's not Spain etc. :-)

I hate the chippings in render finish, it just flakes off and makes a mess around the outside of the house not to mention catching yourself on it while working outside.

Mark S.

[IMM]

right!!!

Houses in wind driven regions: Ireland, Cornwall, Brittany, Wales, Scotland, etc, always render to keep the water "out".

Very rare, especially when people are in a house. Moisture laden air from outside has to enter the house and then the moisture levels is increased by human activity.

If you say so. You could clad the exterior in old combi's, now that will keep the rain off.