1st floor beam and block v timber floor Price comparison

[Canski]

Hi everyone,

 

One of my developer clients has suggested that I may like to look at beam and block with UFH for my first floor design. This appeals to me because apart from the more robust feel and a relatively simple process of installing UFH to the first floor it will also give myself and my bricklayers continuity of work during the build.

 

Has anyone done a cost comparison between timber and beam and block first floor ? I suppose its not an easy exercise when you have to take into account the cost difference between the 2 UFH installation methods but anyway its a question that has come into my head.

 

Thanks in advance for any advice and pros & cons of going down this route.

 

 

[Temp]

We have b&b with UFH on both floors. Can't comment on the cost as it was all hidden in builders quote.  I know some changes to ground floor walls were required - had to go for denser blocks where windows concentrated loads into narrow piers.

 

Upstairs it made tiling the bathroom a breeze. No issues with having to reinforce wood floors for tiling bathroom or levels. 

 

In some rooms, instead of screed we fitted battens with ufh between and 21mm engineered oak on top. (Aside: Note that wood flooring must be 18mm+. Don't buy 14mm and then have to put another layer under it as that would affect UFH performance). 

 

 Was first time our builder had done a b&b first floor. Said he liked it.

[Canski]

54 minutes ago, Temp said:

In some rooms, instead of screed we fitted battens with ufh between and 21mm engineered oak on top. (Aside: Note that wood flooring must be 18mm+. Don't buy 14mm and then have to put another layer under it as that would affect UFH performance). 

 

 

 

 

I was thinking screeding it throughout though not sure if pumped screed or boomed up on the tele handler. Just out of interest how did you combat the cambers in the beams using your method ?

[Iceverge]

Precast 1200mm wide X  150mm thick concrete hollowcore planks here with  75mm concrete poured over the top and some mesh. 

 

Very quick to install as craned from the truck in one afternoon. 

 

The 75mm concrete took any deflection out of the planks. Probability overkill and ended with a thick floor. A 25mm screed would probably have been fine. 

[Canski]

16 minutes ago, Iceverge said:

The 75mm concrete took any deflection out of the planks. Probability overkill and ended with a thick floor. A 25mm screed would probably have been fine. 

I doubt that would be sufficient to cover the UFH ?

[Iceverge]

Ah yes. I forgot about that. 

 

Typically with well constructed new builds heating is not required upstairs save a few towel rads maybe or electric UFH over tiles. 

 

We have no central heating at all....

[Indy]

A topic I am very interested in myself and have been trying to get a comparative cost to see what would be cheaper.

 

From speaking to the architect, a few things that came out:

 

Concrete floors - either beam and block or hollowcore will be quite thick and need a further void put in to run services/MVHR ducting. This may be an issue and reduce available head height in the rooms if that's a constraint for you. Concrete floors will also add to the weight of the building naturally and may mean more substantial foundations or SE designs. Will also cost more.

 

Timber floors - in the form of metal web joists are the usual option and offer flexibility in the sense that the ducting can be run through quite easily.

 

One option that's been put forward as a halfway house is a Lewis/metal deck on top of the timber floors with a concrete screed on top of this. Offers the best of both without increasing floor makeup too much. 

 

I've not seen that before so would be interested to hear from anyone who has gone for that setup?

[Temp]

22 hours ago, Canski said:

 

 

 

I was thinking screeding it throughout though not sure if pumped screed or boomed up on the tele handler. Just out of interest how did you combat the cambers in the beams using your method ?

 

Didn't really notice much camber once the blocks were fitted. If there was any it was taken up in the screed/insulation.

[Russell griffiths]

Cons, you will probably need a crane to install beams or planks. 

So £6-700 for that, unless you can get a big truck with hiab. 

100mm void needed below for ducts. 

[Canski]

48 minutes ago, Russell griffiths said:

Cons, you will probably need a crane to install beams or planks. 

So £6-700 for that, unless you can get a big truck with hiab. 

100mm void needed below for ducts. 

Yeah I’ll put that into the calcs but I could lift the beams for both houses in a day I think so not such a great cost. I also think I will be able to drop my soil pipes straight down from the first through the ground floor and out. I could just do with a void beneath the beams to run pipe work, cables etc. 

[Russell griffiths]

42 minutes ago, Canski said:

Yeah I’ll put that into the calcs but I could lift the beams for both houses in a day I think so not such a great cost. I also think I will be able to drop my soil pipes straight down from the first through the ground floor and out. I could just do with a void beneath the beams to run pipe work, cables etc. 

Do you not have MVHR. 

[Canski]

3 hours ago, Russell griffiths said:

Do you not have MVHR. 

Not planned it yet 🧐

[Russell griffiths]

1 hour ago, Canski said:

Not planned it yet 🧐

Oh Lordy. You had better think about that quickly, it needs a massive amount of room, you can’t just stick it in a 25mm void, it needs 100mm clear space under that floor for it. 

[Canski]

1 hour ago, Russell griffiths said:

Oh Lordy. You had better think about that quickly, it needs a massive amount of room, you can’t just stick it in a 25mm void, it needs 100mm clear space under that floor for it. 

Ok thanks I'll check tomorrow how many of the last 70 or so houses that I have built for well down developers over the last 3 years have MVHR fitted. 

 

[saveasteading]

It is simple really, and related to clear span and load.

Planks span a long way but are heavy to lift, a pain at any changes in dimension, and have a significant camber. Commercial use usually. Specialist installation. 

Beam and block can span further than timber and are more solid, and lend themselves to middling spans, light commercial.  If a house is designed to suit, then can compete with timber. Builders can install.

Timber is for domestic spans, much easier to adapt to changes in shape, and can be cut/joined/nailed as required. Plus extra bits are available at any time.

[TonyT]

Isn’t it a 150mm void for ventilation purposes?

[Canski]

52 minutes ago, Canski said:

Ok thanks I'll check tomorrow how many of the last 70 or so houses that I have built for well down developers over the last 3 years have MVHR fitted. 

 

Oh dear tiredness typo 🤷‍♀️I should have said ‘well known’ thinking now ‘well successful’ 

[Russell griffiths]

8 hours ago, Canski said:

Ok thanks I'll check tomorrow how many of the last 70 or so houses that I have built for well down developers over the last 3 years have MVHR fitted. 

 

Well that depends on what you are building. 
a quality house for you and your family. 
or your general standard developer finish. 
the former will require a robust ventilation system. 
the latter will not as it will probably have trickle vents and extractor fans. 
if it’s highly insulated and a good airtighness then you have no choice. 
just past building regs with insulation values then probably no need. 
just depends what you are trying to achieve. 

Edited July 12, 2022 by Russell griffiths

[redtop]

I have said this before, but.... If you double the building regs level of insulation, half the air Leakage to 5ish then you don't need mvhr and the house will be far far better and cheaper to run than a min building regs house. Chuck in a load of the rockwool noise insulation between floors. Not as good as passive of course, but a lot better than standard for sure and no more complex than a standard build with just extra expense for insulation and a bit of reasonable care over holes / gaps.

[Adrian Walker]

On 10/07/2022 at 23:11, Indy said:

 

 

One option that's been put forward as a halfway house is a Lewis/metal deck on top of the timber floors with a concrete screed on top of this. Offers the best of both without increasing floor makeup too much. 

 

I've not seen that before so would be interested to hear from anyone who has gone for that setup?

 

Someone on Grand Designs used a Lewis/metal deck and concrete in with a timber frame.  The real benefit of a concrete floor is lack of noise. Velox make a concrete floor/ceiling system that uses woodcrete modulars which are 500 x 2000mm - https://icfsystems.co.uk/floors.html

[Raine]

 

Resurrecting this thread as I have a similar decision to make.  

 

@Canski, did you go for beam & block or posis in the end?  Do you have any cost comparison calcs or anything else that may be helpful in making such a decision?

 

 

[Canski]

2 hours ago, Raine said:

 

Resurrecting this thread as I have a similar decision to make.  

 

@Canski, did you go for beam & block or posis in the end?  Do you have any cost comparison calcs or anything else that may be helpful in making such a decision?

 

 

I went for pozi joists in the end. I would have much preferred a beam and block floor but a few things put me off. 

1) the fact that I don’t think that we will need much heat upstairs anyway
2) the cost of the extra masonry to raise the height to give me a service void. 
3) I would have had to beef up my blockwork load bearing capacities and I was tight on the u values of the blocks as it was

 

 

[Iceverge]

Have you considered normal lumber. 

 

It's straight off the shelf in most cases and much cheaper than pozis. 

 

Add a run of resilient bars underneath and you have a nice service cavity for wires. 

 

Obviously waste pipes and MVHR ducting won't fit but design dependent you might be able to work around this. 

[saveasteading]

Normal timber is favourite for small spans. Easy to adapt/ join/ buy/ replace/ cut.

[Raine]

 

21 hours ago, Canski said:

I went for pozi joists in the end. I would have much preferred a beam and block floor but a few things put me off. 

1) the fact that I don’t think that we will need much heat upstairs anyway
2) the cost of the extra masonry to raise the height to give me a service void. 
3) I would have had to beef up my blockwork load bearing capacities and I was tight on the u values of the blocks as it was

 

Thanks @Canski.  Did you install wet UFH with the posis?  If not, do you have no heating on that floor, or rads / elec mats? 

 

Good point on the U values too.  Something for me to bear in mind as the design fleshes out and I get SAP calcs done.

 

I have spans of ~6m so solid timber is a no go, I assume.