Scratch render queries - any advice/opinions much appreciated.

D

dougray

New Member
Hi all, this is my first post but I've been lurking around for a few months before we get our house rendered. Not looking to be a PITA for the guy doing the job by acting like I know it all, I just like to understand how things work and the forum has been great in giving me a bit of insight so thanks for that.
You oracles of knowledge are probably all be fed up with questions from people who are about to get their houses done but I'd appreciate your advice or confirmation whether I've got the right end of the stick on any of the stuff I'll mention below so feel free to chip in about anything where you can lend wisdom, or just tell that I'm a clever boy and it all sounds OK :estudioso:.

It is a pretty standard detached, brick cavity wall house which was roughcast then painted over at some point long ago. A lot of it is bossed so we decided to get the whole lot re-done. I hate roughcast and so does the other half so it's going to be a smooth render. I know a lot of people in Scotland seem wary of smooth render (and I think I understand the reasons) so that's made it trickier to get someone.
We finally managed to get a reliable guy lined up after several let downs, have spoken to four previous customers (inc. two contractors who use him regularly), all glowing references and visited two previous jobs so I could see his work and decide between a smooth (sponge?) or scratch finish. Saw a house he did with white scratch render last year and it looks really good up close. So I feel happy with him doing the work, I now know I want a scratch render finish and the initial quotes (based on these finishes) seem fair. I've already asked him a load of questions and don't want to keep pestering him with more so I figured I could put it all down here.
  • He said he has experience with a most of the systems: Alumasc, Enewall (Powerwall?), Stonepack and a few others so if I had a particular preference, the materials options could be discussed. He seemed to be of the opinion that Alumasc was maybe a slightly better product but enewall would probably be a little cheaper so he recommended using one of those. I know a few people on here seem to rate Enewall (is powerwall the same as Enewall and they have rebranded as he also referred to it as powerwall/smoothband - maybe it's just a generic term he uses?) but I don't know much about Stonepack or Alumasc. Would any of you have a particular preference in terms of flexibilty/durability/resistance to cracking or discolouration? Are any of their scratch renders higher or lower in polymers or fibres that will help them last longer? Or are t hey all much the same in your collective opinion? I would lean towards Enewall as a relatively local company at a good price. This is probably my main query.
  • In terms of prep, he is going to hack off all the old render on both gables where most of the surface is already knackered and remove any bossed patches on the elevations, then use the appropriate adhesive/base coat for the system and fully mesh. From what I've gleaned on here that sounds about right? I was a bit unsure on not removing every bit of the old render but saw on the Enewall site that they suggest hacking off sound render can damage the brickwork so going over with a suitable?
  • My main reservation about a scratch render was keeping it looking nice and I accept it probably won't be maintenance free. I know silicon renders are more resistant to algae and dirt etc. but I suspect will be much more expensive and don't come with the same scratched back finish (or do they?). Upsides: we are nowhere near a main road so no traffic pollution or dirt, the roof overhangs by over a foot around all walls so there shouldn't be too much water regularly running down the walls, it isn't super insulated so there should be enough heat through the walls to stop them staying damp and it is usually fairly breezy. Downsides: there are a fair few trees about and its Scotland so wettish ;)... Would it be worth applying a protector/sealer at the same time as the render. When I asked about this he didn't think it was that necessary but I'd rather avoid a problem than have to sort it later on if it makes a big difference. If we do this, what would you say is the best product as a balance between cost and effectiveness. I found a few threads where the Enewall micro emulsion sealer was recommended.
  • We will probably get new windows at some point in the future, are stop beads usually used around window frames? Would this potentially allow us to do the windows without destroying the render in the reveals?
I think that's everything that was floating around in my head and if you bothered to read it you're a better man than I!
Cheers, Dougie.
 
Let him use whatever material he's comfortable with, enewall is decent gear.

Get him to roll 2 good coats of micro emulsion over it a week after it's been done for extra piece of mind.

Get your windows in before render, damage is inevitable and mono patches are unsightly however well done.

You wouldn't be pestering him asking him this stuff, you'll be spending a fair whack of money and trusting him so questions are fair game.

Good luck.
 
Thanks mate, advice appreciated. Will just go with Enewall and put on the enewall protector. TBH we probably won't have enough to afford the windows for a few years as we've plenty other things to spend the money on with this house, but the rendering can't wait so will have to make the best of it. Is the damage usually limited to the reveals?
 
flynnyman said:
what do you think would happen?
Click to expand...
Not what you are expecting from Ewi.
You can ask the question have I done it over cavity wall and the answer will be yes. The only time I have done it was during the green deal period when the government had to absorb the money for it and the mess is very little especially when you have failed render. Saying all that in this case you don’t have the benefits of Ewi - thermal insulation between the internal part of the wall and the external weather conditions. The cavity completely eliminate that . In this case you will have heat loss from the internal wall to the cavity and here is where the Ewi in this case is just render, nothing else. Saying all this, don’t forget I don’t see the benefits of cavity wall for traditional building.
 
Hi again, I looked at EWI but as we already have cavity wall insulation - loved finding that out while I was core-drilling the wall on a windy day... It seems a lot of extra money for a relatively minimal gain. Thanks for the suggestion though.
Turns out I had my wires crossed re. materials anyway. He had been saying he usually uses alumasc or powerwall when he's doing a straight smooth render, not scratched finish (that's what we initially discussed before I knew I wanted scratch). He indicated the other scratch render job I'd seen of his was done with K-Rend (K1 I think) and he also uses Stonepack scratch render if the budget is a bit tighter.
Is there anything between the two? I've seen a few people knocking K-Rend (maybe just for being a pain to apply rather than as a product when it's on the wall?) but then plenty saying it's fine if the job is properly prepared. The K-Rend site goes on about their scratch render having silicone added to it for better water repellency, is this unique to K-Rend, or is this the norm for all scratch renders? I couldn't see anything about silicon additives on the stonepack site.

Cheers.
 
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