Floor joists

[davejura]

Hi folks. We are building an "upside down" house, timber frame with cement render cladding. We were planning on beam and block on the ground floor (there is quite a lot of under build), but not planning on underfloor heating as it will be the bedrooms downstairs. Our architect is suggesting timber ground floor joists as they will be cheaper, quicker and with not having underfloor heating, all we need. My idea was to get the foundations, under build and beam and block done before the winter, with a solid base ready for the kit in the spring. Anyone have any thoughts and ideas of price difference? Our footprint is approx 80 square metres, maximum 7m width.

Mrs is still keen on underfloor heating. Is there a good way of fitting this upstairs in the living area when we have timber joists? So many decisions to make ...  Thanks.

[Conor]

If you are going to put UFH in anywhere, put it downstairs, as the heat will rise anyway.

[Russell griffiths]

7 hours ago, Conor said:

If you are going to put UFH in anywhere, put it downstairs, as the heat will rise anyway.

Don’t really agree with this, yes it’s true heat rises. 

Butyou don’t want bedrooms over hot just so some heat can rise up a staircase, bearing in mind the upstairs floor will be heavily insulated. 

[Russell griffiths]

@davejura at your area block n beam will only take a day to put in, then another day to insulate, and a day to screed, so it’s not really a long job. 

I would think timber will take longer and not be something you can leave exposed over winter

have you priced block verses timber. 

I think block will be cheaper 

things to be aware of, block will take up a lot more depth to install. From under beams to top of finished floor. 

[nod]

I’m with Russel here 

To get the benefit from UFH in the living areas The heat in the bedrooms would be stifling in the ground floor beds

You can put UFH on the first floor

(timber )  

[ProDave]

There is nothing to stop you having a suspended timber floor upstairs and having UFH upstairs.

 

You can still have UFH downstairs but make sure each bedroom has it's own zone and it's own thermostat so you can have cool bedrooms if that is what you want.

[jack]

9 hours ago, Conor said:

If you are going to put UFH in anywhere, put it downstairs, as the heat will rise anyway.

 

This isn't my experience.

 

We have UFH downstairs and no at all heating upstairs. The upstairs is very noticeably cooler in winter, despite us having a very large stair opening and several square metres of double height area above the kitchen.

 

My theory is that, in a well insulated house, the floor temp required to maintain a comfortable temperature downstairs isn't enough to cause convection currents that would bring the heat upstairs (naturally some makes it up, or upstairs would be freezing). 

[Conor]

My comment was a bit hurried... I was meaning UFH in communal spaces and wet rooms downstairs.

 

Interesting to read that it may not convect... I'm used to radiators that get very hot, heat the air and chuck it upwards. Our upstairs is always warmer than downstairs. May have to rethink my strategy (UFH in basement, and just hall and bathroom downstairs)

[CC45]

If I did my heating system again I'd put ufh upstairs as well as down stairs.  We've put in rads upstairs - no complaints but they weren't any cheaper and the rooms would be more flexibly without rads on walls.

 

 

[scottishjohn]

thats what i did and never regretted it,but i did insulate upperfloor so there was little heat transfer to anywhere but where i wanted it

and as far as keeping upstairs cooler --they are called doors-you have them shut if you wish to keep upstairs a different zone than downstairs

and SHE would not accept not having windows open at night anyway -and as  every room has its own stat --not a problem 

Edited June 16, 2019 by scottishjohn

[CC45]

each room upstairs is on a separate stat with us as well.  No point heating rooms we don't use very often.

[Oz07]

Recently had a quote for 80m2 single storey ufh system. Most of the suppliers are speccing 6 thermostats! Ridiculous for a system all on one floor with a low response time. Would it even be possible for 1 room to be a different temperature to another? Like 5-10 deg c? Told them to change it to two zones. Bedrooms bathrooms and kitchen lounge dining

 

Also cannot get ufh down to rad prices perhaps you all overpay for rads and pipework?

[scottishjohn]

If you using rads with low temp UFH type of water --then you need rads twice the size --or expensive ones heat excahanger look like a car radiator+ fan assisted -not just flat like std rad.

If you want very quick response on ufh --then don,t use big thick slab.

If you put a layer of insulation on top of main slab ,then ufh in a thin screed --that would alter reaction time

If you want big temp diffs from one room to next then you will need doors that fit well and a more complicated MVHR--no 10mm gap as normally used under doors

[ProDave]

1 hour ago, Oz07 said:

Recently had a quote for 80m2 single storey ufh system. Most of the suppliers are speccing 6 thermostats! Ridiculous for a system all on one floor with a low response time. Would it even be possible for 1 room to be a different temperature to another? Like 5-10 deg c? Told them to change it to two zones. Bedrooms bathrooms and kitchen lounge dining

 

Also cannot get ufh down to rad prices perhaps you all overpay for rads and pipework?

Both our last house and this one have a thermostat per room.  Definitely in the last house we could turn down the unused rooms and they really would stay cooler, providing you kept the door shut.

 

Have you considered DIYing your own UFH. The material costs are really not that much, a  manifold, a coil of pipe or 2, and some controls.

[Oz07]

Good suggestion @ProDave I'm guessing thats what a lot here have done?

 

Im not too confident with working out all the maths side though. Could I just pinch the designs i've already been sent. What kind of markup do you think these suppliers are adding?

[CC45]

I just ordered the bits from Wunda (they did the design) - pretty straightforward.  I'd never done one before but would do another no prob.  give it a bash.

[Oz07]

Got the quote form Wunda. Seems a bit more sensible than others. Also seems more suited to DIY or maybe thats just my interpretation of it. Question of cost now. Around 950 ex VAT for UFH.

 

What would a 8 Radiator system cost with TRV's and pipework? £60 per rad excl labour?

[PeterW]

1 hour ago, Oz07 said:

What would a 8 Radiator system cost with TRV's and pipework? £60 per rad excl labour?

 

What size....? Decent rads are £50-70 for a 4x3 room, TRV is £12 for a decent one. Go to designer rads and you will be north of £200 per rad.

[Oz07]

Deffo not designer!

Small rads as low output needed. I reckon 60/70 then pipework and sundries for system 2-300?

[CC45]

I spent as much on rads & pipe work as I did on all the UFH downstairs.  My experience is that there's nothing in it.  I'd do what feels right.  Our next house will have UFH upstairs.

[Cpd]

On 23/06/2019 at 12:57, PeterW said:

What size....? Decent rads are £50-70 for a 4x3 room, TRV is £12 for a decent one. Go to designer rads and you will be north of £200 per rad.

I’m still looking into rads for upstairs and ufh downstairs. If you have recommendations for good quality fan assisted rads to run of the low temps put out by an ASHP I would be interested as there seems to be a wide cost difference in these..... I am thinking fan assisted as i am interested in as fast a response time as possible.