Floor Reconstruction in 70's Bungalow - Advice needed.

redbeaard

I'm renovating an early 70's bungalow in rural Donegal. Doing a fairly big job on it, knocking some internal walls and building some new ones. It's 100sq meters (approx 1000 sq feet), heated with stove with back boiler and no underfloor heating.

Currently have we have a screed (1in ->3in), DPM, hardcore (3in ->5in), sand + stone mix (more than a 20in).

The levels of the hardcore are very uneven which dictates the thickness of the screed.

I have already decided to lay a new screed layer sas this will level the floor on the different sides of the internal walls I am removing and also allows me to deal with slightly over the limit radon levels and patches of damp which is most likely caused by some dodgy plumbing (sinking new pipes without replacing DPM).

So my question, do I
1. Remove existing screed, flatten existing hardcore, lay new DPM and new screed. No insulation. No concrete slab. This is just replacating whats there but with new materials. Is the concrete slab necessary?

2. Remove existing screed, flatten existing hardcore, lay new DPM, add new floor slab, add thin 20mm layer of insulation (somethig like this Alutherm stuff), add screed.

3. Remove existing screed, flatten existing hardcore, lay new DPM and new floor slab. Add insulation, maybe 50mm. This will raise the level of the existing floor so would need to slope floor down to existing external door frame, shouldn't be too much of a slope. Ain't going to raise lintels in existing internal doors so could just trim off a bit off the bottom of each door as needed.

4. Remove existing screed, remove existing hardcore, remove enough depth of sand/ stove mix to allow me to replace all that with what is now typical in a new build eg. hardcore, DPM, concrete slab, 150mm insulation, screed. This option is going to bloody expensive and taking out all that extra stuff is going to be a seriously labor and time intensive.

So they are some rough options that I can think of right now. This is quite honestly wrecking my head at the moment. We're already on a pretty tight budget and even tighter schedule and this is something I hadn't factored in at all. I know new building have strict specifications for these things but really is the insulation that worth it in this situation?

All advice and opinions greatly appreciated.

BryanF

with the limited info offered, id focus on insulation & the radon issue

so i vote for option 4

with structural eng on board knock int walls, dig out floor, install services, proper Radon sealed with sump vented!, insulation, screed to eng spec

redbeaard

Cheers BryanF

I've had separate builders in during the week and they're all of the same consensus - dig out as much as needed to keep the floors the same level as original as much as possible, add hardcore, layer of sand, radon barrier/DPM, as much insulation as I can afford but no less than 100mm and at least 3 inch screed. No need for concrete slab.

I suppose I should contact an engineer too just to be sure.

BryanF

redbeaard wrote: »

Cheers BryanF

I've had separate builders in during the week and they're all of the same consensus - dig out as much as needed to keep the floors the same level as original as much as possible, add hardcore, layer of sand, radon barrier/DPM, as much insulation as I can afford but no less than 100mm and at least 3 inch screed. No need for concrete slab.

I suppose I should contact an engineer too just to be sure.

that'sno less than 100mm PIR (kingspan or similar) yes?