Filling void under suspended floor

[Lamentable]

Hi John,

DPC: I will lift some boards and find out. I have a feeling it's a sort of slate between layers of brick, which based on what is visible on the garage which sits slightly lower than the rest of the house it's around 1 or 2 bricks below floor level in the rest of the rooms.

For what it's worth (I guess very little) the survey when the property was purchase did not indicate any areas of concern for damp.

Air Bricks: Marked with red arrows.

The "Sitting Room", "Dining Room" and Kitchen are suspended floors. The Entrance hall is concrete.

Filling in the Sitting / Dining room would leave the kitchen on a suspended floor for now although I plan to rework that entire area in the future. The kitchen would have two remaining air bricks

Drain Gullies:
At the back of the house there is one for the kitchen sink and one for rain water.
Right side of the house there is one for rain water.
Front of the house there are two for rain water.

The slugs mostly appear in the sitting room near to the external wall (right of image).

 

[JohnD]

The sitting room and dining room appear to have plenty of airbricks, providing they are not choked and are not low enough for water to run in. How far above ground or paving level are they? Do you ever get puddles against the house?

The DPC should be visible outside the house, and at least nine inches above ground or paving.

Where are the drains? Please photo

Do you have clay gullies?

How old is the house?

 

[robinbanks]

you need 100mm bearing on both leaves

Beams do not bear on both leaves of a cavity wall

 

[noseall]

Beams do not bear on both leaves of a cavity wall

No kidding.

'Both' as in both inner leaves. It's impossible to inset a beam without poking through one side 200mm. On a 50mm cav wall, that means a hole in the outer skin on one of the walls.

 

[robinbanks]

If you review the image in the original post, you'll find that only one of the bearing walls is external

 

[blup]

Isn't the ventilation needed because of the wooden joists so if they no longer existed it wouldn't be required?

(I'm not a builder)

I'm not sure there is any damp. I think the slugs just "wonder" in through the air bricks then find there way up through the floor boards.

Blocking air bricks can restrict through flow of air to other rooms with suspended floor. It can sometimes be a problem with solid floor extensions to older houses with suspended floors. Slugs are attracted by food and lay eggs in its vicinity.

Blup

 

[JohnD]

Blocking air bricks can restrict through flow of air to other rooms with suspended floor. It can sometimes be a problem with solid floor extensions to older houses with suspended floors. Slugs are attracted by food and lay eggs in its vicinity.

Blup

Drain leak, yum yum.

 

[blup]

1.2 metre void, ideal crawl space.

Blup

 

[noseall]

If you review the image in the original post, you'll find that only one of the bearing walls is external

If you review my post history, you will see I posted before any images were available - hence the content and previous warnings (Christ, this is hard work this morning).

 

[phatboy]

- Find the cause of the likely leak, digging in a 4ft space with a mini shovel isn't the worst job (except in this weather)
- Fit mesh to the air bricks to stop slugs getting in
- Insulate between the floor beams to improve heat retention, and also ensure nothing can get up into the room
- Fit heating onto new sub-floor layer
- Relax

Will be quicker, cheaper, cleaner and just as good as filling in with many, many tonnes of type 1 and concrete. And you won't need to move out to do it. You'll also still have a space to put anyone who dis-pleases you!

 

[Lamentable]

I've also considered exactly this.

Can I fit a wet system on top of floor beams and solid insulation boards? What then goes on top of that? Some sort of screed?

 

[phatboy]

Yes, and these guys are excellent - https://www.wundagroup.com/water-underfloor-heating/joisted/

I used a system of theirs for my extension, but not for that floor type. They did the design for me and specified a kit. They say trade only, but were quite willing to help.

 

[Lamentable]

Just had a look.

Is it better to have a system embedded in screed so that it works more like a storage heater?

Also on their website, they say about running the system at 50 deg. C. but Karndean quote a much lower temperature.

Thanks in advance.

 

[robinbanks]

Having both in the same house I'd say "yes, screed embedded pipes are definitely a lot better than any 'pipe in a tray' type system"

I don't bother running the heat spreader plates UFH upstairs any more; the ground floor screed runs at 27 degrees and serves the whole house, though upstairs is sometimes a bit cooler than I'd like. If I had the time over again I would have done the same as what the guy who specified my house heating/insulation did; upgrade the timber joist spec and pour a liquid screed upstairs too

It massively depends how much you want to chase the perfect solution. You're on a retrofit so everything is harder, but if you dropped your floor 195mm, had 150mm of kingspan, 40mm of screed, 5mm of karndean, upgraded the rest of the thermal envelope to a similar spec you'd be heading toward a point where you didn't even need a heating system. Some measure of compromise is present in everything, insulating your timber ground floor and having an overlay system might be cheaper to the extent that it takes years for a "worked slightly harder" heat pump to cost more than upgrading the fabric..

My personal bias is to fabric upgrades and reducing energy consumption rather than saying "ah, **** it, that substandard approach will do and I'll just burn more heating oil/gas/electric"

 

[Lamentable]

I'm currently in the process of getting some quotes to fully fill the floor and to see where that leads in terms of time, disruption and cost.

I'll investigate the damp / water ingress issues at the same time.