Putting down a concrete floor in a period house

hotpotato

Hi!

Could any nice person fill me in on whether pouring a concrete floor in a period terraced house on the ground floor strikes them as a good bad idea? Whaty would be the advantages and disadvantage of this do people think?

One of the disadvantages that is said that any small amount of water would collect and not be able to evaporate as it would if there had been floor boards. This make sense?

BryanF

hotpotato wrote: »

Hi!

Could any nice person fill me in on whether pouring a concrete floor in a period terraced house on the ground floor strikes them as a good bad idea? Whaty would be the advantages and disadvantage of this do people think?

One of the disadvantages that is said that any small amount of water would collect and not be able to evaporate as it would if there had been floor boards. This make sense?

What's driving the change to concrete? And why are you expecting water?
Whats the ground level externally like relative to the internal level?

Any dis/advantage is quiet site specific.

sarkozy

I was going to start a thread on this subject precisely as we're facing the same decision and looking for cost-effective and sensible options.

In our case, our house is of solid redbrick construction with shallow foundations on impacted earth. The floor is raised off the ground slightly, joists/beams nearly touching and floorboards about 6 inches from the ground. The original ventilation grilles are, I think, still in situ allowing cross ventilation. There is, what I would consider, a normal amount of moisture/condensation entering the interior of the house through rising damp or damp earth below the foundations, and this is naturally cleared away by evaporation and drafts. Exterior ground level does not seem to need to be lowered and not by much, if at all.

Essentially, the house hasn't changed in this regard since it was built.

We want to insulate the roof and external walls. I'm concerned that dry-lining the walls, doing the attic and installing replacement wooden double-glazed sash windows might trap moisture in the rooms. Laying an insulated concrete slab (making the house more airtight and dry overall) could lead to moisture being trapped within the house, leading to problems. This would then require us to undo all our work at great expense. Alternatively, we could spend a fortune on the DPC/insulated concrete slab when laying down a vapour barrier and underfloor insulation would do the job just as well.

So, the long and the short of it is to do one of the following:
* Lay the concrete slab because it's good for the house and will solve any dampness issues
* Lay a vapour barrier and under-floor insulation and that should solve the issue more cheaply
* Do nothing.

What are the pros/cons, options?

I hope my question will help the OP's question, too.

hotpotato

What he said. Thanks Sarkozy!

sarkozy

Another thing I've read up on today is that laying a vapour barrier might cause the floor itself to become colder leading to other kinds of dampness issues.

I really need to call in an expert to advise. Happy for recommendations via PM.

By the way, hotpotato, I've never had any luck on this forum asking about this topic. We seem to be as clueless as each other.

BryanF

sarkozy wrote: »

1. facing the same decision and looking for
2. cost-effective and
3. sensible options.

• solid redbrick construction
• shallow foundations on impacted earth.
• The floor is raised off the ground slightly,
• joists/beams nearly touching and floorboards about 6 inches from the ground.
• The original ventilation grilles are, I think, still in situ allowing cross ventilation.

4. what I would consider, a normal amount of moisture/condensation entering the interior of the house through rising damp or damp earth below the foundations,
5. and this is naturally cleared away by evaporation and drafts.
6. Exterior ground level does not seem to need to be lowered and not by much, if at all.

• We want to insulate the roof and external walls.
• I'm concerned that dry-lining the walls, doing the attic and installing replacement wooden double-glazed sash windows might trap Laying an insulated concrete slab (making the house more airtight overall)

7. could lead to moisture being trapped within the house, leading to problems.

• This would then require us to undo all our work at great expense.
• Alternatively, we could spend a fortune on the DPC/insulated concrete slab when laying down a vapour barrier and underfloor insulation would do the job just as well.

So, the long and the short of it is to do one of the following:
8* Lay the concrete slab because it's good for the house and will solve any dampness issues
9* Lay a vapour barrier and under-floor insulation and that should solve the issue more cheaply
10* Do nothing.

11. What are the pros/cons, options?

I hope my question will help the OP's question, too.

hotpotato wrote: »

What he said. Thanks Sarkozy!

1. why are you both facing this decision alone? why have you not consulted with an architect who specializes in retro-fits and can advise on the site specific ramifications
2. site specific
3. site specific
4. site specific
5. as above - how do we answer this? where will the moisture go if you install a concrete floor. will the dry-lining system be so designed to allow for the evaporation of any rising dampness? etc
6. we take you word for it, but you don't seem sure about much else...
7. it could : as per 1,2,3,4,5,6
8. is it 'good for' the house? and will it solve the dampness: it could be BUT as per 1,2,3,4,5,6
9. it could do BUT as per 1,2,3,4,5,6 - will it just cause the problem to migrate up behind your dry-lining, and 'out of sight out off mind' allow mould to fester to the determent of your home and family..
10. as per point 1.

BryanF

sarkozy wrote: »

I really need to call in an expert to advise. Happy for recommendations via PM.

good man.

By the way, hotpotato, I've never had any luck on this forum asking about this topic. We seem to be as clueless as each other.

both of your situations could be completely different, and may need completely different approaches. you cant tell that over the net. all you will get is what can go wrong or others experiences, neither of which can be relayed on.

sarkozy

Thanks, BryanF. You're right of course. We've been consulting an architect with experience of period renovations since the beginning and, to be honest, I don't think he knows. For example, his drylining specifications mentioned Kingspan K17 mechanically fixed to the external wall, but when I asked about cold bridging effects arising from this, rather than affixing insulation to battons, he didn't seem so sure beyond what Kingspan advised and has not suggested consulting with an expert.

Regarding the underfloor, it's the same thing.

We want to do what is right for the house, but we're also very restricted in our budget.

BryanF

what depth of pir ?

i weould not recommend ufh unless you surpass the current buidling regs as regards insulation and thats rarely suitable where one is drylining a 30's external wall