what insulated floor construction for above a basement

[hallega]

Can anyone advise on the best way to have an insulated floor above our new basement? Part of the house will be on ground level and the other with a basement beneath, I'm wondering how I can merge the two floors and make it as insulated as possible? 

The original design didn't have a basement, this was an afterthought. 

Durisol blocks used throughout. Daughter has used warm floor beams, but she's only got a void underneath, not a basement. 

[Temp]

Is the basement going to be a heated/habitable room or just for storage?

 

One option is to build a beam and block floor over the whole footprint and put insulation and screed on top.

 

[Bitpipe]

Does the basement have a concrete lid or suspended timber? And will the ground floor have heating in it?

 

If it's concrete then the above suggestion is probably the best way to go - create a contiguous ground floor and work off that.

 

You'll find basements, however they are insulated themselves (internally or externally) do not have a very high heating requirement as they will maintain a year round ambient temperature due to being in the ground. If they're full of plant or equipment (TVs etc) then that all helps.

 

Our basement is a passive design and has no heating at all but it's a full footprint so does not give us the issue you have.

[Mr Punter]

You would not normally need insulation to a floor above a basement.

 

Bear in mind that the basement design may need a certain floor type to help support the walls.

 

You will need to be careful if you have a suspended floor in the other part of the house as it would normally be ventilated and therefore cannot connect to the basement part.

 

As per @Bitpipe, a full basement saves quite a few issues.

[Conor]

I'm not sure if you have started building or not, but this very complicated detail is why we committed to a full footprint basement as all the insulation would be in the foundation slab. Doing a partial basement on our site made no sense.

 

Otherwise, some sort of concrete slab (hollow core or block and beam) with DPM, 150-200mm PIR and then screed would be the way to do it. Avoiding cold bridging between your basement walls and the suspended floor slab will be critical.

[hallega]

Too late now for a full basement, I had enough trouble getting the council to agree to this one! I had to go through all the permitted basements in the area to get them to bend on it!

Block and beam and the insulation on top seems to be the way to go then. My basement is half in the ground, not fully, I live on a hill. It will have the ground source and MVHR stuff in there and hubby wants underfloor heating too, if it's needed then at least it's there. Constantly trying not to get any cold bridging Conor, looks like we may have to have a sleeper wall inside of the durisol blocks so this doesn't happen, not sure yet, we are moving slowly rather than rushing into everything, it's all a new learning curve for the hubby (74) as he's very old school.

Put in a door in case we need to get out if there's a fire, thought that was sensible, but that brings other problems, like retaining walls and now a tiered garden...blooming heck...who thought this was going to be easy, you should see the reinforcement around the sumps x 2 !

Thanks everyone, taken on board all suggestions, glad your here to help. Photo's attached....even I am shocked now by the amount of re-bar!

[Bitpipe]

Brings back memories  We had 16+ tonnes of rebar in our 120m2 basement.

 

If you have sumps then assuming you've chosen internal membrane as your waterproofing method, did you consider other methods (e.g. waterproof concrete)? Pertinent to other threads at moment.

 

I will say I'm a bit surprised that the insulated ground floor was not addressed at design stage but sounds like you have a plan.

 

What made you decide on ground source for heating? Doesn't seem that popular a choice anymore now that ASHP is more widespread.

[hallega]

Bitpipe, we have the area for the ground source and I believe that ASHP is not as effective in lower temperatures, we are 500 feet above sea level here and when it snows we have it for a week and 4 miles down the road it's all gone!

Internal and external delta membrane waterproofing, french drains  

We intend to put in a swimming pool and ASHP will heat that as it's more efficient and economical to heat the pool in the summer months, complicated life eh!

I found out yesterday that a LOT of concrete is going to have to go in to hold this house , great news...Loads of money ! 

My fault that this house doesn't quite fit any criteria as I designed it on "home by me" online, sent it to a CAD op man, then learnt auto cad (not very well by the looks of it) and altered the plans......ooops! THEN decided to add a basement...can you see the problem...hahahaha...I saved 30 grand on an architect and am now putting it back in the ground...O'h well!

It should look like this when it's built.....fingers crossed....

our new house.pdf

[Ferdinand]

54 minutes ago, hallega said:

We intend to put in a swimming pool

 

Just checking that you have found this thread:

 

[AliG]

Not sure if you only posted a picture and no plans, it says 3 downloads but I only see a PDF picture.

 

Is the pool outside or inside? I am guessing maybe outside if you plan to heat it in the summer.

 

I did a lot of work on the cost of heating a pool. Basically if you put a pool outside, heating costs are high as there is very little to stop the heat escaping. However, you don't need to worry about dehumidifying which is expensive on my indoor pool.

 

The biggest thing that helps is for the pool to have a proper cover as a lot of the cost of heating a pool is that warm water evaporates from the surface of the pool and is then replaced by cold mains water which needs to be heated up. Stopping the evaporation stops this heating cost.

 

Depending on the size you are probably looking at 100kwh a day to heat an outside pool, according to what I can find online. So that is £3 in mains gas or £4 in electricity via a heat pump. This is a very rough guess depending on the size of the pool, how hot you want it etc, turning the temperature up considerably increases the costs so people normally run outside pools colder, around 27C. You will also spend quite a bit on electricity for the filter pump, a few hundred a year.

 

I would question why you would install a separate ASHP and not just use the GSHP to heat the pool. You will be looking at a multi thousand bill, so even if it has a slightly better COP in the summer it won't offset the extra cost of another heat pump. If you have mains gas available I would just use that. Electricity currently costs more than 5x the price of gas, not enough for the COP of a heat pump to offset plus the installation costs are considerably cheaper. We heat the whole house and pool from a standard Bosch 40kw boiler.

[hallega]

AliG,

No we don't have mains gas, had to rely on oil for the past 33 years...! I had a pool in my other house, outside and it was run on gas then, we had a pool cover but not as good as they are nowadays. My son runs his pool on his ground source in the summer only but he really doesn't know how much his electricity bill is as he leaves it all to the wife...must ask her then!

I do however have 32 solar panels on my stable roof so really I should be using that energy eh. I did hear about the costs of de-humidifying an indoor pool and got put off, much as it seems nice to be able to swim all year round, I've heard horror story's of peeling plaster etc., 

I shall think again about the ASHP, thanks for the advice.

Thanks to ferdinand for the thread.