Damp or stains on paint?

[Jacko1992]

Hi,

We have recently purchased (July 19’) a circa 1900 property, 3 bed semi detached. We fully painted the entire house and noticed some strange almost stain looking marks on the external front wall of the house in the front room. Some are directly under the bay window and the other, much larger, is in the corner of the room behind the TV / above the gas meter.

They don’t feel wet at all, no paint particularly comes off when you touch or rub them and they haven’t changed much or at all from what I can tell. We used Dulux Matt emulsion paint and we've actually got a few patches on the gable end wall upstairs in the bedroom as well. When you shine a torch on them they have a glitter effect... is this salt? Or a previously applied oil or paint of some sort applied to the wall or even a problem with our paint? They weren’t visible before we decorated but the wall was painted a darker colour and it was July! They did appear as the paint dried though so within a day or two you could clearly see them. The second patch (pic 2) on the right hand side of the bay seems to have recently appeared although I might not have noticed it before now. We live in Manchester and it has rained a lot recently!!

There is a vent bang in the middle under our bay window which is always open and not blocked. We have a plant in the window and thats it, we never close the curtains. Not noticed condensation on the windows. External to the wall is a flagged drive and directly under the wall vent is an air brick for under the floor. I did place a standard Aero360 dehumidifier in the corner of the room a few months back and its filled up a few times but only three times in three months. I'd have thought it would have filled up more if we had a big damp problem.

IMG_1958 (002)

• Jacko1992
• 4 Nov 2019

Any help much appreciated!

 

[JohnD]

the small mark under the windowsill looks like rain penetration, but the large mark looks like severe long term damp.

Is it a concrete floor, or wood?

If concrete, lift the carpet and see if the concrete is damp.

If wood, lift the concrete, and a board, and look and sniff underneath.

Please photograph the other side of the damp walls.

Some common causes are:

• earth or paving above the level of the DPC
• Spilling or leaking gutter allowing water to splash on the wall
• Broken drains causing high water beside the wall
• Leaking pipe (may be watermain or radiator pipe) feeding water into the ground or foundation.
• Bath or shower on the other side of the wall with water penetrating the sealant or tiles

Have you got a water meter?

Does your boiler have a pressure gauge?

Has some idiot raised the ground level beside the house?

Are you on a slope allowing rain to run towards the house?

Did the house come with some kind of (worthless) damp-proofing guarantee?

p.s.
tape a piece of clear plastic tightly to the wall and see if mist or water droplets form on either side of the plastic. Which side?

 

[Jacko1992]

Hi John

I’ll have to take some pictures of the outside of the walls tomorrow in light and post. We’ve had new carpets fitted but there was some new floor boards coming from that corner of the house. There isn’t a damp smell... it is the external corner of the house and I’ve read that they tend to be the coolest parts a room? Surely there would be damp at the base of the wall all along the skirting if it was wet? The wall isn’t wet to touch?

The fact that that is the gable end and has all been repointed (maybe last 5 years?) and looks like it’s had injection DPC (round filled holes across front and all down side of the house) plus some floorboard replacements in that area makes me feel it’s a previous issue? What about the sparkle when you shine a torch on it? Is that a sign of something?

Yes boiler has a pressure gauge? Radiator is at other end of room so not sure if there would be a pipe there for that. Ill have to check on water mains but I don’t know if it runs there or not!

 

[Jacko1992]

My girlfriend just pulled up a picture of before we decorated... you can see replacement boards.. can’t be a coincidence??

 

[JohnD]

looks like it’s had injection DPC (round filled holes across front and all down side of the house)

that tells me two things

1) it's had a damp problem

2) whatever the problem was (groundwater, gutter, broken drain, leaking pipe) has not been repaired but they hoped that putting a chemical in the bricks would prevent the water showing. They might have replastered the walls with magic plaster as well.

Silicone injections never cure building defects. Damp is pretty sure to be due to excess water and/or a building defect. It won't be cured until you find the source and fix it.

As you've seen, the damp-roofing was useless.

This is normal.

Yes, have a look under that board.

The sparkle might be mineral salt crystals left behind when the water evaporates. If you find enough, scrape them off and see if they fizz when you drop them in vinegar.

look for the DPC as well. It's probably a slate bed in the mortar course nine inches above where the ground level was when the house was built. it might be easy to spot near a doorway. Slate lasts about a hundred million years.

Pressure gauge on the boiler means that if you had a leaking radiator pipe, you'd see the pressure drop.

Take lots of photos.

 

[JohnD]

p.s.

the floorboards in front of the fireplace look "cupped" to me. This is a form of warping when they come up at the edges (they can also come up in the middle) and the patch of ply over the hearth looks water damaged. Possibly the chimney is relevant.

 

[foxhole]

Those old terraced houses often have very poor brickwork which allows penetrating damp especially around and near windows .

 

[Jacko1992]

Chimney was in bad shape when we bought the property. It had loose bricks at the top and mortar was poor. Had both chimneys “dropped” to lower level, fully repointed, all the flashing and roof checked / sorted and they have NOT been blocked. Fully aware they need to breathe. All of the chimneys (this house has three) have air vents. This chimney has two, air vent at the back on gable wall outside and in our bedroom above.

pressure for boiler seems fine; boiler was serviced before we purchased.

Gutters have been fully cleaned both inside and out about 6 weeks ago. Down pipe runs at the front of the house; right near that corner. Will check if any splash but not noticed anything... the brick work looks dry.

Dont think we have slate DPC; already checked around house and can’t see anything.

Water mains run under the road / path in front the the house a fair distance away (20ft or so). Plus next doors house/gable is only 3 ft away (3ft ally runs between both gables) from our gable end so would imagine they’d have issue if large leak? Checked our search pack.

 

[foxhole]

Are any external wall rendered?

 

[Jacko1992]

Nope. The entire house is brick, I’d never render as I know this can trap moisture in the wall. As discussed; the entire gable has been repointed low down to about 6 ft and possibly something to do with previous issue?

I think the bay could do with being repointed to be honest. The mortar is pretty old and it’s that thin red type if you know what I mean. Not sure if this is the cause of the damp there or possibly the window (or combination of both). It’s the corner I’m concerned about.

Think I’m going to get a chartered surveyor in to take a look. I’ll be staying clear of these ‘damp gone’ companies.

 

[JohnD]

Gutters have been fully cleaned both inside and out about 6 weeks ago. Down pipe runs at the front of the house; right near that corner. Will check if any splash but not noticed anything... the brick work looks dry.

How does the water from the back of the house get to the drain or sewer? For example, is there some kind of underground drain running past the side of the house?

You can't see a DPC, but I think there very likely was one when the house was built. Is it in an English town?

 

[Jacko1992]

The bathroom is at the back of the house and the soil stack is there as well. They could either run directly under the house or potentially around the back. I’m not sure if there is a way to find this out? I know the drains are again under the main road at the front of the house so it’s a possibility they go underneath or out of the back and then loop around somehow? I’m pretty sure we’d be able to smell a leaking drain underneath considering it’s just carpet and then floorboards though?!!

It’s a town just outside of Manchester; not far from Salford. There is 100% no slate hanging out anywhere around the house.. we have air bricks under all of the floors downstairs which I’ve cleared out in the past few months so I’ve been pretty close to that area so would have noticed if this was the case.

I will post pictures when I get home tonight of the corner and bay with the flash on my phone. Didn’t have chance this morning as was in a rush!

 

[chris1982]

Perhaps ask your neighbours about their DPCs?

 

[JohnD]

drains in Victorian houses in areas I know, run around the back and sides (not under) the house or terrace, then out to the street to join the road sewer.

There may be separate rainwater and foul water drains.

Downpipes at the back and sides are usually at the corners and the underground drain often laid in straight lines between them. Your house probably has glazed clay gullies, and these are IME always cracked, broken and leaking, usually at the bend. Possibly Salford is different, but towns that were bombed 1939-45 usually have drain damage.

Some districts have a lane or alley at the back, and services may be laid there.

 

[martin hill]

The damp behind the tv is it the same sort of height as under the window. ?