Damp/mould in the conservatory on the wall against the house

Adam · 7 Apr 2023 at 16:01

Moving on to trying to make the conservatory useable. We tried when we first moved in but found it unusable due to it always being too hot/too cold depending on the time of year. I channeled out the wall for cables and hung a TV bracket/ikea cabinet to hide the cables. During the past 5 years it's been used as a place to store my daughter's toys.

I've noticed over the past couple of years that there is some mould/damp on the wall where the conservatory backs on to the house. It's on both side of the french doors.

There's no sign of any damp coming from the roof so I am guessing it's coming up through the floor somehow. You can just about to see some damp course in the 2nd picture but I don't know if it's enough.

We had the wooden floor laid when we moved in but I am prepared to lift it all up if needs be.

Any thoughts on what could be causing this or what I can check/do to rectify it?

Fuzz · 7 Apr 2023 at 16:38

Skill builder on youtube has a great video on an almost identical issue... render touching ground below DPC and allowing damp to creep up I think.

Fuzz · 7 Apr 2023 at 16:45

I'm lacking decent internet in deepest cornwallcestershire at the moment but it's called something along the lines of " damp wall and how he fixed it"

SpellowHouse · 7 Apr 2023 at 17:05

Could also be coming from the wall above the conservatory (if there is one). Water enters a brick wall and travels downwards. Normally an exterior wall will not be painted on the lower section like that, so it will travel down without any trouble. But if you paint it you can trap it in the wall, causing issues. If there is any brickwork outside above the conservatory, then you need to coat it with a water seal. A single coat in the summer with a sprayer will last five years. Cleaning off the internal wall and painting it with a damp proof paint will stop any more coming through. Paint it all the way to the bottom with the skirting board removed.

Adam · 7 Apr 2023 at 19:33

Fuzz said:
I'm lacking decent internet in deepest cornwallcestershire at the moment but it's called something along the lines of " damp wall and how he fixed it"

That was enough thank you. I have managed to track the video down that I think you are referring to.

Seems to be this product here which looks straight forward: https://www.amazon.co.uk/Dryrod-Dam...421-4d20-a20f-b2ad51a85fa5&pd_rd_i=B07XZ7NCH5

SpellowHouse said:
Could also be coming from the wall above the conservatory (if there is one). Water enters a brick wall and travels downwards. Normally an exterior wall will not be painted on the lower section like that, so it will travel down without any trouble. But if you paint it you can trap it in the wall, causing issues. If there is any brickwork outside above the conservatory, then you need to coat it with a water seal. A single coat in the summer with a sprayer will last five years. Cleaning off the internal wall and painting it with a damp proof paint will stop any more coming through. Paint it all the way to the bottom with the skirting board removed.

Looks like something like this is what you are suggesting which again looks cost effective and easy to apply: https://www.amazon.co.uk/Everbuild-...8c2-48a4-b462-237e21f95dfd&pd_rd_i=B0012LETNK

Very helpful thank you!

Fuzz · 7 Apr 2023 at 20:26

Less drop out now, everyone must be eating dinner :cry:

I think it was this one I saw recently.

SpellowHouse · 8 Apr 2023 at 08:27

Adam said:
Seems to be this product here which looks straight forward: https://www.amazon.co.uk/Dryrod-Dam...421-4d20-a20f-b2ad51a85fa5&pd_rd_i=B07XZ7NCH5

Looks like something like this is what you are suggesting which again looks cost effective and easy to apply: https://www.amazon.co.uk/Everbuild-...8c2-48a4-b462-237e21f95dfd&pd_rd_i=B0012LETNK

Very helpful thank you!

Yes, something like that. Just make sure you don't get it on the glass. Cheap plastic cover works just fine.

Lean · 8 Apr 2023 at 09:13

A couple of thoughts. Has any of the silicone perished where the brick sill sheds water? You have a photo in your paving thread where the mortar seems to also be retaining moisture in that corner.
I've used those rods with mixed results.

Adam · 10 Apr 2023 at 19:17

Lean said:
A couple of thoughts. Has any of the silicone perished where the brick sill sheds water? You have a photo in your paving thread where the mortar seems to also be retaining moisture in that corner.
I've used those rods with mixed results.

Here's a better image from the other side. The bricks do look damp (this was taken yesterday before today's downpour).

The damp is going all the way across the conservatory where it backs on to the original house wall, would damp from one corner do that?

There also looks to be some gaps in the mortar, that's the level with the DPM. Maybe I should look in to getting that replaced as well.

Slam62 · 10 Apr 2023 at 19:33

I would lift the adjacent flooring and see if it's wet underneath. It could be a legacy of the flooding and just needs to dry out.

Stu999 · 10 Apr 2023 at 19:46

Is there a DPM there?

gingergundog · 10 Apr 2023 at 19:55

Take out some bricks and check your cavity for bridging.

Lean · 11 Apr 2023 at 06:48

Tricky one if it's right the way across the internal wall. I was going for penetrating damp if it was just in the corner.
You had the conservatory down pipe that seemed to be discharging into a flower bed if I'm remembering correctly. Pop the laminate and chipboard up for s look underneath.

SpellowHouse · 11 Apr 2023 at 08:56

Point the camera up.

Adam · 11 Apr 2023 at 18:34

SpellowHouse said:
Point the camera up.

This is how it looks from inside the conservatory. If the damp was coming from above, wouldn't there be signs of it travelling down the wall?

Adam · 11 Apr 2023 at 18:42

I took the advice of @Slam62 and lifted the laminate floor board. The plywood and insulation is not damp at all nor are there any signs of any damp. That makes me think the damp is not coming from under the conservatory but is related to the house wall which the conservatory joins to.

It looks like the plaster has been applied directly to the face of the brick. Any plaster under the DPM is damp and comes away very easy. Anything above it takes a lot of force to remove, sounds different when you try and remove it and isn't damp. You can see the thickness of the plaster in one of the images. Anything below the DPM just crumbles.

Another thing to notice is the laminate floorboard only shows signs of any damp on the edge directly against the wall. Whatever the cause of this is has occurred over a long period of time, it may have been made worse by the patio work I had done but I know there have been signs well before it was done which we have turned a blind eye to. The other side of the patio doors are the same too.

The white trunking is for a Sky coaxial cable which was run from the dish through one side of the conservatory and over to the other side. You can see where it enters the house. That isn't required anymore due to the SkyQ boxes so I am tempted to remove it entirely just in case it's contributing to the issue. The trunking runs up against the brick it seems.

Fuzz · 11 Apr 2023 at 19:37

There we go, exactly as I said, render has been put over the DPM and sucked up the dampness in the ground.. Pretty much identical to the video I mentioned (and later found)

Adam · 11 Apr 2023 at 20:00

Fuzz said:
There we go, exactly as I said, render has been put over the DPM and sucked up the dampness in the ground.. Pretty much identical to the video I mentioned (and later found)

I think you are right. Having watched that video again I think that’s exactly what it is.

Looks like it saves me some money rather than having to install the dryrods too. As long as the render is removed and mortar replaced (but not touching the DPM) it should solve the problem. I will also tidy up the mortar on the outside as well.

Lean · 11 Apr 2023 at 20:03

Lets find where the water has been getting in now. So you have a solid floor, DPM and air bricks. Are the air bricks around the conservatory ducted through the slab to go under your suspending floor in the main house? If not then they arent doing much but to let moisture in which will be migrating to the edges where it is getting sucked up by the plaster (as mentioned above). Go poke something through the air brick to see if you hit the slab. Also how long was the roof draining into that raised bed or whatever was there before?

Fuzz · 11 Apr 2023 at 20:32

Lean said:
Lets find where the water has been getting in now. So you have a solid floor, DPM and air bricks. Are the air bricks around the conservatory ducted through the slab to go under your suspending floor in the main house? If not then they arent doing much but to let moisture in which will be migrating to the edges where it is getting sucked up by the plaster (as mentioned above). Go poke something through the air brick to see if you hit the slab. Also how long was the roof draining into that raised bed or whatever was there before?

It's totally normal for the footing to be damp, that's why you have a DPM.
What has happened here is that the previous (original) exterior wall has been rendered over and rendered straight over the DPM and onto the footing brickwork, this has allowed the render to suck up the dampness and wick up the wall.
The reason the floor isn't affected is that has it's own DPM (layer of plastic anyway) under it when it was laid for the new conservatory floor. It's clear as day in the pics posted.