Rendering to ground..... do or do not?

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HoogaB

New Member
Hi, I'm new to construction and am building a passivhaus. I've been messed around and stolen from by a dodgy.... but that another story... however it has left me cautious..... and now I have a rendering issue I was hoping to get some impartial advice on please.

In short, it is EWI system with external render. The builder (new team) has put a scratch coat on, it's all needed nicely except at the base. The builder doesn't believe a bead is needed. Personally, I don't want a bead and a black colour underneath as it spoils the look of the house. Loads of properties in Spain, Italy, Germany are done this way.... so is it ok to do, knowing that each year it may need a clean???....

1. The front of the house has raised steps which creates a false external floor level. The dpc is well below this and we have a couple of inches of air an air gap between the raised steps and the wall. There will also be a channel drain around the perimeter. So he doesn't think a bead profile is needed.

2. At the rear, there are overhangs from the floors above of 1.2m. It creates a Brie solei so no rain hits the wall, or very little. Again a channel drain at the foot just in case any build up of standing water. So he thinks we can go to floor again.

3. The sides of the house and garage done benefit from a Brie solei or a raised floor level. It's a full wall to ground level. There will be a stone/pebble perimeter of circa 1.2m wide by circa 80mm deep around the perimeter to create natural drainage. I am more worried about this area because it's to ground level, with natural drainage.

They are planning on doing a silicone based thin coat render over the top.

I can upload photos if it helps?

Thanks
 

zombie

Private Member
Hi, I'm new to construction and am building a passivhaus. I've been messed around and stolen from by a dodgy.... but that another story... however it has left me cautious..... and now I have a rendering issue I was hoping to get some impartial advice on please.

In short, it is EWI system with external render. The builder (new team) has put a scratch coat on, it's all needed nicely except at the base. The builder doesn't believe a bead is needed. Personally, I don't want a bead and a black colour underneath as it spoils the look of the house. Loads of properties in Spain, Italy, Germany are done this way.... so is it ok to do, knowing that each year it may need a clean???....

1. The front of the house has raised steps which creates a false external floor level. The dpc is well below this and we have a couple of inches of air an air gap between the raised steps and the wall. There will also be a channel drain around the perimeter. So he doesn't think a bead profile is needed.

2. At the rear, there are overhangs from the floors above of 1.2m. It creates a Brie solei so no rain hits the wall, or very little. Again a channel drain at the foot just in case any build up of standing water. So he thinks we can go to floor again.

3. The sides of the house and garage done benefit from a Brie solei or a raised floor level. It's a full wall to ground level. There will be a stone/pebble perimeter of circa 1.2m wide by circa 80mm deep around the perimeter to create natural drainage. I am more worried about this area because it's to ground level, with natural drainage.

They are planning on doing a silicone based thin coat render over the top.

I can upload photos if it helps?

Thanks
No 1 rule in rendering dont render below dpc
 

Brimstone

Well-Known Member
Photo's would help. Had to look up Brie Solei to check it was what I though it was - however there are a lot of variations. There is a reason why its not done much in the uk and that's because of climate. No, it is not the same as Germany/Europe.
It depends upon the site exposure but most of the UK can at some point can get near horizontal rain and it will get past the screen. Several days of rain/damp and it will not dry out, and could casue a problem.
I suggest you put your artistic preferences to one side and accept the practical fact that a drip/base plate and band under may be the best going forward. You can always paint it to match the rest and repaint from time to time.
 

algeeman

It’s A Boy
I thought a brie solei was an Ice lolly
20220620_121124.jpg
 

essexandy

The Lake Governor
Hi, I'm new to construction and am building a passivhaus. I've been messed around and stolen from by a dodgy.... but that another story... however it has left me cautious..... and now I have a rendering issue I was hoping to get some impartial advice on please.

In short, it is EWI system with external render. The builder (new team) has put a scratch coat on, it's all needed nicely except at the base. The builder doesn't believe a bead is needed. Personally, I don't want a bead and a black colour underneath as it spoils the look of the house. Loads of properties in Spain, Italy, Germany are done this way.... so is it ok to do, knowing that each year it may need a clean???....

1. The front of the house has raised steps which creates a false external floor level. The dpc is well below this and we have a couple of inches of air an air gap between the raised steps and the wall. There will also be a channel drain around the perimeter. So he doesn't think a bead profile is needed.

2. At the rear, there are overhangs from the floors above of 1.2m. It creates a Brie solei so no rain hits the wall, or very little. Again a channel drain at the foot just in case any build up of standing water. So he thinks we can go to floor again.

3. The sides of the house and garage done benefit from a Brie solei or a raised floor level. It's a full wall to ground level. There will be a stone/pebble perimeter of circa 1.2m wide by circa 80mm deep around the perimeter to create natural drainage. I am more worried about this area because it's to ground level, with natural drainage.

They are planning on doing a silicone based thin coat render over the top.

I can upload photos if it helps?

Thanks
Assuming that you're using grey EPS as the main insulation (?) that definitely shouldn't go below the damp course.
 

HoogaB

New Member
Hi all, thanks for the replies. This is what we have on site currently and having chatted it through with them today, he says that they basically go to the floor. The doc wraps underneath the insulation and up the wall and is painted with black bitumen paint, which is easily seen on sections where the wall covering will be stone on an Nvelop system.

The top coat goes over the grey liquid applied roof finish on the balcony area and then they have a different Atlas rendering product, he called it a mosaic, which is used at the base. He said this is a waterproof product that protects and acts to stop any water ingress. His view is that beed will do nothing. It is the water proof finish at the base that is important and that is the atlas mosaic product (which is white) or a tile where it is flush to floor.

At the front of the house (the second to last pic) where we have a raised area across the entire house, there will be a tile finish and a tile upstand.

The last pic shows the rear where the tile would be used like the front.
 

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Elite exteriors

Well-Known Member
Hi, I'm new to construction and am building a passivhaus. I've been messed around and stolen from by a dodgy.... but that another story... however it has left me cautious..... and now I have a rendering issue I was hoping to get some impartial advice on please.

In short, it is EWI system with external render. The builder (new team) has put a scratch coat on, it's all needed nicely except at the base. The builder doesn't believe a bead is needed. Personally, I don't want a bead and a black colour underneath as it spoils the look of the house. Loads of properties in Spain, Italy, Germany are done this way.... so is it ok to do, knowing that each year it may need a clean???....

1. The front of the house has raised steps which creates a false external floor level. The dpc is well below this and we have a couple of inches of air an air gap between the raised steps and the wall. There will also be a channel drain around the perimeter. So he doesn't think a bead profile is needed.

2. At the rear, there are overhangs from the floors above of 1.2m. It creates a Brie solei so no rain hits the wall, or very little. Again a channel drain at the foot just in case any build up of standing water. So he thinks we can go to floor again.

3. The sides of the house and garage done benefit from a Brie solei or a raised floor level. It's a full wall to ground level. There will be a stone/pebble perimeter of circa 1.2m wide by circa 80mm deep around the perimeter to create natural drainage. I am more worried about this area because it's to ground level, with natural drainage.

They are planning on doing a silicone based thin coat render over the top.

I can upload photos if it helps?

Thanks
Don't bridge the dpc
 

Brimstone

Well-Known Member
Okkkk, builder has obviously thought about it. You might want to discuss holding a retention sum for 12 months, he might not be ok with that if not part of the original deal or, see if you can buy an indemnity. (Maybe for the whole build?)
As you are requiring this, as opposed to the builder suggesting it, (which you are), then if it fails its with you not him. He's used reasonable care and workmanship, and has proposed a solution which seems viable, not negligent.
 

themucky1

Well-Known Member
Any insulation below dpc needs to be xps not eps, tanking slurry behind the xps from the ground to minimum 200mm above eps base track, double meshed with waterproof render and ideally finished with a mosaic render finish similar to texture
 

HoogaB

New Member
Any insulation below dpc needs to be xps not eps, tanking slurry behind the xps from the ground to minimum 200mm above eps base track, double meshed with waterproof render and ideally finished with a mosaic render finish similar to texture
I had this conversation with him today and he assured me that below dpc is fine. If it's below ground level, then they have used XPS. He even drew me a diagram. The outer wall layer of insulation is graphite eps, whilst the inner layer at the bottom with the slopes slanted angle is xps.

I do think there maybe a couple of places where the ground layer is very close to the eps and I queried that he has of course said it's not an issue and the eps won't draw water up.

Do you know anywhere, maybe building regs doc, that confirms you can't use eps below the dpc?

Thanks
 

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essexandy

The Lake Governor
I had this conversation with him today and he assured me that below dpc is fine. If it's below ground level, then they have used XPS. He even drew me a diagram. The outer wall layer of insulation is graphite eps, whilst the inner layer at the bottom with the slopes slanted angle is xps.

I do think there maybe a couple of places where the ground layer is very close to the eps and I queried that he has of course said it's not an issue and the eps won't draw water up.

Do you know anywhere, maybe building regs doc, that confirms you can't use eps below the dpc?

Thanks
Just out of interest, have you used a flow screed or traditional sand and cement?
 

HoogaB

New Member
Base coat looks terible and the fixing pattern is wrong.
I got conflicting info on fixing pattern and process. Some said don't overlap at joins and fix points near centre. Others said to fix in the joins. Fill with expandable foam or render glue?

The fixing pattern does seem a little random. We were short on Ejot fixings and more are to go in. They are all glued/bonded also.
 

Brimstone

Well-Known Member
I saw that on the photo. To give the building a get out of jail card, the bottom pic was from my neighbours work that we did. It's the raised patio area wall. Not great but not structural and will be behind a cement render then tile finish. The top one is another garden wall that will be stone clad and cement rendered first.
And the blockwork with no gauge or apparently mortar at all? Good spot by Dollar
 

Brimstone

Well-Known Member
To which image are you referring?
If it's the white block, then they are glue bonded together. No mortar.
The grey ones and the white ones, almost any pic with brick or blocks in it. Proper glue bonding requires, or should require, careful cuts and precise placement and not using the bonding mix as a filler - as appears to have been done on that corner.
But it's done now and will probably be fine, with render over nobody wil ever know..except us
 
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