"Imperial damp, not metric" 😂

My 1920s house had multiple damp issues mainly due to breached dpc and damage clay drainage. 4 years ago I reduced the ground level around the house and replaced all drains. Now the house breathes and has dried out lovely.

I'm a damp expert and the chances of any house ever needing a new DPC is so low. You need to find the cause, not treat the symptoms. The external ground level 100% needs lowering and they need to find the original DPC as long as the building was built after 1875 it will have one. When you find the original DPC you then need to make sure your ground level is 150mm below the DPC.

Kids with drones are epic for inspecting roofs and gutters. It's one job they'll do without being forced into it 8)

Exactly the problem I had in my ground floor flat.  I kept getting lung infections and the renting agency said "open a window" ffs.  The outside had been built up over the damp course.  Having no door step is a give away.  The people laying the new surface couldn't be bothered to dig up the old one properly I guess.

I’ve recently (just in time for Christmas) finished a similar repair in my 19th century house. When we moved in in the summer there was a down pipe more-or-less running into a subterranean air brick; there was a frog in the hole and a pool of water under the floor. All missed by the surveyor of course. First job I did was a two course surround to the air brick. Then sorted the gutters. Dug out about 30 bags of soil under floor. Had to replace all the sister joists (clearly this is a long standing problem) and about a third of the floor. Used C24 timber, lots of anti rot treatment and DPM. In the spring I’ll be looking at the exterior. Great fun!
Great video on Skill Builder as always. Thanks Roger for your work.

If you look at the old paint on the wall, the floor looks to be there and above the vents.

Hi Roger. Please keep up the good work. You are appreciated 👏

That cement path is a massive wick leading to his wall.

Air vents tell the story the floor where obviously above them and possibly somebody lowered the floors to gain head room because a lot of old buildings had very low ceilings

I've got this on my relatively new build house (built in 2008) Some idiot did an extension back in 2016 wayyy before I moved here in 2023.

We have rising damp on the extension, got a damp specialist company to come and fix and if anything it's got worse. Literally don't know what to do, so stressful

The same twonk also decided to build a garden room on wooden sleepers with no weatherproofing on the base so the foundations are literally rotting away

"Get out in the rain and see what's happening" Such good advice! The stormier the better - water gets new powers of penetration when its mate the wind shows up! Plus - get up into any lofts etc with a good torch once you've done the outdoor bit. On the job in the video - locate the external side of those air brick holes. My guess is they are covered over or at ground level. If they are at ground level, find a way of baffling them so that groundwater and splash can't get blown through to the inside skin across the cavity. Even fitting periscopes won't help as they'll just act as drains down on to the sub floor if the external levels and details around the airbrick exteriors are wrong.

I had old house with some bricks that hadn't been fired properly. They were like mush.

If the underlying issue isn't sorted, which is clearly that path too high over the DPC and blocking the air bricks, there's not much point replacing stuff inside.

I had damp in a back room but after watching your channel realised before getting in damp proof cowboys that it was a series of problems combining. Some cowboys had piled all the plaster rubble from a fireplace job under the floorboards bridging the DPC, I had lino laid over an adjacent kitchen quarry tiled floor (laid on earth 1930s style, so need to breathe), I had concrete round the outside of the property too close to tge DPC so cut that back and made a gravel filled trench around the house, and the rear bay window flat roof had never been guttered so rain ran off that splashing up on the bay brickwork, so I fitted mini guttering. I also used the damp proof cream on the lower few brick courses above DPC. I got a dehumidifier to speed up the drying out which took about 18 months. All of these jobs sorted the problem. You have to get to the root cause and there might be several.

If the dpc/dpm isn't installed correctly how long before it shows sign of damp issue etc

Australian structural engineer here. Love your advice, spot on. You really need that ventilation under the floor… I’ve seen many horror stories where it’s all been blocked up. Must be a hundred times worse in the UK.

Would surface drainage sort that?

@skillbuilder

Hi Rodger
I was delighted to see the picture I sent in on a thumbnail on my Youtube home screen. I am a Big Skill Builder fan

Thanks, I really appreciate you taking the time to review it.

Just to clarify a few points:
The original joists were pocketed into the wall and were completely wet and rotten inside the pockets. That’s why I installed a timber wall plate bolted to the wall with DPM behind it instead.
I also installed polythene on the floor.

Regarding the air bricks, you are right it is a mystery why they are at that hight. My best guess is that they were originally combustion air vents, intended to bring fresh air into the room and then feed the fireplace via the chimney draw.

If you look closely at the photos I sent, you’ll see I have in fact installed telescopic vents to redirect airflow under the joists. I also installed a vapour barrier under the joists, added insulation between them before floorboarding over.

The holes visible in the brickwork weren’t from me installing dry rods, they were from a previous damp proof course. I injected the walls from the outside in with DryZone DPC Injection Cream in the mortar course above those bricks and then made good with some mortar (hard to see in the photo).

However, when winter came, I noticed damp returning, mainly after heavy rain. I wasn’t sure whether the cream hadn’t fully cured yet or whether it hadn’t properly penetrated the inner mortar bed of the internal skin. This is when I thought to send it in to you guys at Skill Builder.

In the end, I decided to install a physical DPC. I ground out the correct mortar course on the internal skin section by section, inserted a modern DPC, and repointed as I went. That wall has now been plastered and has fully dried out — even with heavy rain during drying — so I’m confident the rising damp has now been resolved.

As a temporary measure, I’ll be patching where the concrete has perished outside this weekend and forming a fall so water runs toward the neighbour’s gully (which isn’t actually blocked). In spring, I plan to lower the external ground level to at least below the air brick under the window (which is under a bit of wood in that picture of the outside) and putting in an ACO drain.

Belt and Braces all the way

Thanks again for covering it

I really appreciate it.

Looking at the photo showing the outside path level, it is way too high compared to the inside floor level.

I disagree with the plastic over the dirt - if the damp doesn't breathe out here it'll squeeze up the wall. It looks like the outside floor is a big problem - lower the path, flaunch it so there's no standing water up against the wall, tidy up the pointing and maybe put some waterproofer on the brick (it doesn't last though) low down. Internally, dry line with a no bridge system. Make sure there's proper air movement under the floor from them airbricks and it there isn't add more. Insulate the floor as if you successfully arrange a howling gale under there it'll be cold if you don't.