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1930's Suspended Timber UFH options?


RedMango

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Hello,

 

Just had an offer accepted on a 1930's Semi typical house, need a full renovation and wanting to future proof it as much as possible as it will hopefully be a home we keep and pass on.

 The house has no insulation, no boiler/radiators (does have a gas supply) It has suspended timber joists 400mm centres thoughout. 

 

I originally planned on a GSHP with UFH but due to cost, budget and not really having the space we are going for a combi boiler (Probably Bosch Greenstar 4000)

 

My questions is whats the best method? From what i can gather in my reserch screed is best and can be done with suspended joists but i need to check that it can take the weight? (assuming i need to get a structual engineer in?)

If they cant whats next best? I've seen the ali spreader plates but not the best reviews as they seem to be noisy and not produce much heat? Also whats the best floor construction after the UFH, do i need a subfloor and if so wont this limit the amount of heat i get through?

 

Any pointers or help is much appriceated, this is the first project ill be taking on and hoping to do it all myself, im an mechanical and electrical engineer so this is new for me but im keen to learn and i have no real time limit to complete.

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Insulation has to be your main priority, also looks like single glazed windows so very draughty. UFH would not supply enough heat without sorting the insulation and droughts first.

Ceilings look high so you can afford to loose some for floor build up but it’s a lot of work with doors etc.

GSHP is a no go unless you have a field at the back.

new windows, roof checked, roof insulation, cavity wall ins then start looking at the other stuff

 

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17 hours ago, bassanclan said:

Check with your mortgage that they will lend on a property with no central heating

I've got a broker that is sorting that, as far as they are concerned it has electric heating. 

 

14 hours ago, TonyT said:

What’s the budget?

doing diy or builder route?

 

Looks like a nice big basement / underfloor area at least at the front!

 

Will be mostly if not all DIY. I need to spend the next 8 months learning 😂 some things I'll get someone in to do if it's more cost effective.

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On 20/04/2022 at 15:54, markc said:

Insulation has to be your main priority, also looks like single glazed windows so very draughty. UFH would not supply enough heat without sorting the insulation and droughts first.

Ceilings look high so you can afford to loose some for floor build up but it’s a lot of work with doors etc.

GSHP is a no go unless you have a field at the back.

new windows, roof checked, roof insulation, cavity wall ins then start looking at the other stuff

 

Yes I'll be starting off with a full rewire, then a full installation. Not sure what the walls are yet but I plan to do external wall insulation down the line.

 

My question really is what's the best layout for the flooring.

 

I'm currently thinking, insulation with a gap for screed and Ufh then engineered wood over the top but do I need to fit a chipboard sub floor between or underlay?  

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Does the house have a basement or crawl space down below? 
If not, have an SE work out if you can do away with the ventilated floor void. I’d dig out, and fill with Insulaton and pour a concrete slab. Cold ventilated floors are the biggest enemy. 
You can have loads of insulation, but a few draughts will instantly negate it. Heating by low temp UFH has been done wrong in these types of dwellings, more things than done right ( correctly / comprehensively ). 
If on gas, consider nice rads, as this type of property requires a LOT of effort and cost to get up to a standard that allows low temp heating. 

Edited by Nickfromwales
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I would be interested to see the makeup of that floor.  If it were a low floor void underneath it would probably be thin joists with intermediate sleeper walls, but with such a big space under the floor it might be larger joists spanning the width of the room.  That would make it easier to insulate properly to a good standard and with a good working space under.

 

Contrary to what most think on here, I have no problem with a well insulated suspended floor with UFH I did that by choice in both my self builds.  With that huge space, I cannot see how you can build it up for a solid floor without the infill putting outward pressure on that very large height you have to build up, and that's one hell of a lot of infill to import to do it. 

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Yes I can't imagine I will want to go the infill route, I agree with you Nick that it would make it easier to keep warm however, as it's only going to be me doing the work, budget and tbh I'm not sure my heating requirements warrant the effort involved. Our current house has more heat loss that this one will and we get by with very minimal heating. 

 

Dave, I to am eager to see the floor construction. I'm going to presume the joists run the length of the rooms (averagely 3-4m) maybe with one or two sleep wall in the middle for support.

 

From the research I think I've decided (if I can)

 

18mm Engineered Wood

Vapor barrier? Maybe?

Joists-25mm screed with 16mm UFH

75mm PIR or the maximum the joists allow

 

If the joists are a lot thinner then I'll probably max the insulation then build the UFH above it on top of the floorboards or a chipboard subfloor. Then screed and engineered wood.

 

The 1st floor I'm going hopefully do the same screed but if it's not strong enough then I'll go for the PIR boards with UHF cutouts. With wood flooring laid on top

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10 hours ago, bassanclan said:

With 30k to play with, fit radiators, forget ufh and save your money for more insulation!

I can go more or less as there's about 100k needing to be spent but 30k is what I have to buy from day 1. Why do you say radiators? I'm not against the idea of that but I just presumed UFH was more efficient especially as in 10+ years we are all apparently going to be running heat pumps 🤔

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Forget ufh. 

Rewire is £4-5 grand

windows £12-15

floor insulation and a bit of woodwork will be £2-4 grand. 

So you have spent 20 in the blink of an eye. 

Don’t try and reinvent the wheel, those houses come up good with a nice rear extension, open plan kitchen. 

You will spend 100 grand in a heart beat. 

Just do good solid work not fancy screed on joists, that will suck you gas meter round like a Catherine wheel. 

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16 minutes ago, Russell griffiths said:

Forget ufh. 

Rewire is £4-5 grand

windows £12-15

floor insulation and a bit of woodwork will be £2-4 grand. 

So you have spent 20 in the blink of an eye. 

Don’t try and reinvent the wheel, those houses come up good with a nice rear extension, open plan kitchen. 

You will spend 100 grand in a heart beat. 

Just do good solid work not fancy screed on joists, that will suck you gas meter round like a Catherine wheel. 

I was thinking of screed-in-joist for my suspended timber upgrade - is it really that bad?

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3 hours ago, RedMango said:

I'm not against the idea of that but I just presumed UFH was more efficient

It will never be as efficient as radiators, because however much insulation is under the floor, some heat will always be lost by conduction into the ground.

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So the general consensus is radiator are better than Ufh in this situation? Not going to lie that goes against everything I've read but I guess most my research has been on Ufh Vs radiators and not been specific to the house type. I'm not to worried about the budget I just wanted it to be as energy efficient as possible and allow me to not pay a stupid amount for gas on 10 years time.

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16 minutes ago, RedMango said:

the general consensus is radiator are better than Ufh in this situation

Yes, but as the heating water from ASHP is only 30 C at best efficiency  , you will need large areas of radiator. 

Some study required, and look into what sort of space you have available.

 

I think there are cleverly designed rads which will disperse the heat more quickly, but that they are quite expensive.

Others on here will know better than I.

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30 minutes ago, RedMango said:

So the general consensus is radiator are better than Ufh in this situation? Not going to lie that goes against everything I've read but I guess most my research has been on Ufh Vs radiators and not been specific to the house type. I'm not to worried about the budget I just wanted it to be as energy efficient as possible and allow me to not pay a stupid amount for gas on 10 years time.

Run the house details through either the mcs heat loss spreadsheet, or the freedom heat pumps sizing spreadsheet (I found this one easier to use and a bit more comprehensive, pm me for a link) and then see whether you can fit the required sizes of rads onto your walls. Start there then move forwards.

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28 minutes ago, saveasteading said:

Yes, but as the heating water from ASHP is only 30 C at best efficiency  , you will need large areas of radiator. 

Some study required, and look into what sort of space you have available.

 

I think there are cleverly designed rads which will disperse the heat more quickly, but that they are quite expensive.

Others on here will know better than I.

 

17 minutes ago, HughF said:

Run the house details through either the mcs heat loss spreadsheet, or the freedom heat pumps sizing spreadsheet (I found this one easier to use and a bit more comprehensive, pm me for a link) and then see whether you can fit the required sizes of rads onto your walls. Start there then move forwards.

 

I wont be using ah eat pump though, just a standard boiler

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37 minutes ago, RedMango said:

 

 

I wont be using ah eat pump though, just a standard boiler

You still need/should be doing a heat loss calc for each room so you can size the rads and the boiler correctly. With part L coming in from June, it will be a requirement anyway.

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10 hours ago, RedMango said:

Our current house has more heat loss that this one will and we get by with very minimal heating. 

If that statement is true, it would be the complete opposite of the 1930's semi that we once owned.  Solid, unisulated walls, meant it leaked heat like it was going out of fashion, cost a fortune to heat 20 years ago, I would not want to be paying the heating bill for it now.  We had fitted better windows and insulated the loft but the basic fabric of the house was poor, and little you could do cheaply to improve it.

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5 minutes ago, HughF said:

Don’t discount air source… do the heat loss calcs and go from there. You’ll end up on one eventually, when the boiler ban in 2032 comes in.

Im hoping a £2k boiler can last me till 2032 then i'll consider it.🤣

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