Suspended wood floor

Stephen_89

Bought a 1970s dormer a bit over a year ago and have had a few suggestions from different contractors on best way to insulate the floor; rigid board, spray foam and filling the floor with hardcore, dpm, insulation and concrete. We were applying for the deep retrofit scheme but papereork has already taken 4 months for the SEAI to still nit habe a response so now thinking of doing the REIL scheme with local CU to do windows, walls and attic separately to floor. Baby due in a few weeks so bit of panic stations given that the SEAI have essentially ignored all complaimts from us and the contractor about the delay. Any advice on the floors is mich appreciated.

1) A few concerns around keeping the suspended floors in general, really bad smell of damp throughout the house and feel this is coming from the floor.

2) A bit of a history even in the last year of leaks in the house, long standing ones, so I am worried that when we begin work we see most of the joists are rotten.

3) Will it actually achieve a decent level of warmth vs filling the floors and laying underfloor heating

4) Dry rot, if we keep the suspended floor and insulate with foam is it liable to encourage dry rot?

Again thanks in advance for any opinions / advice!

Stephen

GreeBo

With suspended floors you need to ensure that you have good ventilation in your crawl space (space between the joists and the ground)

I presume your house has external vents that are visible from the outside? Make sure these are not blocked up...often someone has raised the ground level outside and its at the same or higher than the vent so letting water in.

Stephen_89

Hi GreeBo, thanks for the response! Yes it has vents all rounds, one of the leaks I mentioned was that bad that water started coming out one of the vents!

GreeBo wrote: »

With suspended floors you need to ensure that you have good ventilation in your crawl space (space between the joists and the ground)

I presume your house has external vents that are visible from the outside? Make sure these are not blocked up...often someone has raised the ground level outside and its at the same or higher than the vent so letting water in.

GreeBo

Timber is pretty resilient to be fair...but if its been getting a constant supply of water then you can be in trouble.

For example, a leaky roof where once a week some timbers get soaked can survive without any issues for years, assuming there is adequate ventilation to dry it.
Compared to a constant small amount of water that keeps a piece of timber damp forever....very quickly this timber will be junk.

If it was me I would be taking up the carpet and some boards in the areas I suspect damage and taking a look to see what you've got.

Pouring a concrete pad is going to be €15-20K.

listermint

Is the roof in good condition? Missing or cracked tiles? Missing grout on apexes or sides? Broken flashing around joins ?

Roof can be obvious source of leaks.

Aside are you losing water from the attic tanks / heating system . I presume it's oil fired with pipes under the floor ?

Stephen_89

Hi both, the leaks have been stopped, roof had some leaks, all resolved now, the floor too had showers that werent sealed right so run off went into floor boards, concerned that the cost of replacing boards will quickly mount up to the same all in as just doing the concrete?? Once you take in the cost of labour pulling up timbers, laying insulation, replasing joists and floorboards, etc. Floor area c. 200m squared. Any ideas on the 'best' insulation method for the floor?

Stephen_89

Sorry, yes oil fired currently with pipes under floor. The pipes are gun barrel so need replacing too, one of the reasons we are considering the concrete and doing underfloor with it. Some whack of thermal mass once it is up and running.

GreeBo

Will you be doing underfloor heating (heatpump?) downstairs or staying with radiators?

BoardsMember

GreeBo wrote: »

Timber is pretty resilient to be fair...but if its been getting a constant supply of water then you can be in trouble.

For example, a leaky roof where once a week some timbers get soaked can survive without any issues for years, assuming there is adequate ventilation to dry it.
Compared to a constant small amount of water that keeps a piece of timber damp forever....very quickly this timber will be junk.

If it was me I would be taking up the carpet and some boards in the areas I suspect damage and taking a look to see what you've got.

Pouring a concrete pad is going to be €15-20K.

Could it be backfilled with hardcore, and then insulation and concrete for UFH? Would €15-20k seem excessive for that?

Stephen_89

Ideally heat pump but may not be able to get the dormer to the min rating for this for the REIL scheme, currently 18 airchanges per hr so pretty much an airtunnel. If we go with filling the floor we would do underfloor rather than rads.

GreeBo

BoardsMember wrote: »

Could it be backfilled with hardcore, and then insulation and concrete for UFH? Would €15-20k seem excessive for that?

Thats pretty much what they do, with insulation and membranes...but you are also taking up all the floors and substructure (joists) and getting the house back into a usable shape afterwards.

i've had 2 quotes of 25K for the same works on a 100sqm area so I just spitballed a reduction...OP what size is the house?

Stephen_89

Ground floor area is about 200m2 so quite hefty