How to do a Maintainable Insulated Floor?

[Ferdinand]

This is for the Little Brown Bungalow project, but may be more useful here in future for reference.

 

The current floor buildup is, from the bottom:

 

Concrete raft.

300mm or so ventilated void.

Suspended wooden floor.

Underlay + carpet or similar.

 

The void contains some water and gas pipework. The question how to maintain this access in future. I am planning a 'floating' floor ... though not completely floating.

 

The intended buildup is something like:

 

Concrete raft.

Ventilated void.

Insulation between joists - 100-200mm rockwool.

Suspended wooden floor.

Vapour / air membrane

50mm Kingspan between battens. It is from Seconds and Co so the battens are to be safe.

18mm OSB, screwed down to battens.

Underlay.

Click fit laminate or carpet, depending on room.

 

The question is how to do the floor so that I can get at the gas / water piping if necessary. I am able to adjust the buildup if necessary to a degree.  I could potentially leave the battens out altogether or not screw them or the OSB down depending on the Kingspan which I will find out when it arrives, and insert a separation membrane to ease movement.

 

Any comments are most welcome.

 

Cheers

 

Ferdinand

 

Edited April 26, 2017 by Ferdinand

[Ferdinand]

(Bump). Comments would be welcome on this one.

 

Ferdinand

 

[ProDave]

The only option I can think is trap door(s) to access pipes.  I doubt you even have enough space to go crawling around under there.

 

[Onoff]

Depending on which way the joists run you could do a stepped service void along one wall.

[Ferdinand]

Thank-you for the comments.

 

At present I have heating plumbing under the suspended floor, which I was hoping to reuse while replacing rads (which would give me effectively oversized rads when I improve the thermal envelope to let the new boiler run more efficiently). Not repiping the plumbing would save several hundred.

 

I have an IWI acoustic wall on one side against the neighbour which is now at batten and noggin stage, and the property is compact. Services could go in there.

 

But I am now thinking about organising my battens on the 'floating' floor to give me uninterrupted service voids along appropriate sides. You have reminded me that I did this several years ago under a floating floor in a conservatory, and it worked very well. Relocating pipework to be wiThin the thermal envelope (planning under suspended floor insulation too as above) is looking a better option.

 

Far tidier than designing all those layers to be easily cut through. Very Occam.

 

Ferdinand

 

 

 

 

Edited April 30, 2017 by Ferdinand

[MikeSharp01]

26 minutes ago, Ferdinand said:

Very Occam

His Razor, the programming language, or just parsimony not at work?

[Ferdinand]

Just now, MikeSharp01 said:

His Razor, the programming language, or just parsimony not at work?

 

The Razor. Unnecessarily difficult maintenance being designed out through stopping for a bit and asking for advice :-).

 

F

[MikeSharp01]

Yes if two competing methods arrive at the same outcome the simpler is to be taken forward and the other summarily shot! Poor old Lorentz....

[Nickfromwales]

Spend a few hundred, get the heating inboard, run a new cold mains under the floor and forget the void exists . 

The gas pipe being 'maintained' is just not going to happen TBH, and if it ever died you'd just find the pipe at the footings and bring it up into an externally mounted meter box. ( why not do that now, and run a fresh gas pipe out, first as last ( not knowing how long your retaining the property of course )). 

 

[Ferdinand]

10 hours ago, Nickfromwales said:

Spend a few hundred, get the heating inboard, run a new cold mains under the floor and forget the void exists . 

The gas pipe being 'maintained' is just not going to happen TBH, and if it ever died you'd just find the pipe at the footings and bring it up into an externally mounted meter box. ( why not do that now, and run a fresh gas pipe out, first as last ( not knowing how long your retaining the property of course )). 

 

 

The property is probably a 10-30 year keeper.

 

It already has an externally mounted gas meter box, and a Nautilus-escue creation of pipework inside the kitchen where it was taken outside. Bet the pipes take up as much space as the old meter box :-).

 

F 

[Nickfromwales]

With a 10-30 year plan, I'd get the fundamentals sorted first tbh. Plumbing and electrics are fundamental IMO, and cosmetics can be retrospectIvely amended with ease, and little disruption, along the way. Get the floor void clear and cover it over, why create extra expense engineering future proof solutions to a problem you can swiftly neutralise now ? 

Now is your most economical opportunity to address these items, so better to spend once now than spend 3-fold later ( and worse if  you have to remove a paying tenant to do so  ). 

[Ferdinand]

Thanks for the feedback so far @Onoff @ProDave @MikeSharp01 @Nickfromwales

 

So, working with this, I get:

 

1 - No pipes under the suspended floor.

 

2 - My battens arranged such that there is a 63mm deep x approx 200mm void all the way round all the walls. Including battens round the edge at the base of the wall.

 

3 - All electric (except that in the loft for lights, fire alarms etc and a few bits in stud wall where appropriate and gas in that void. Also water pipe and signal cables where necessary.

 

4 - Void filled with insulation just like the rest of the floor where unused, but probably round the outside walls as far as possible. For future adaptability.

 

5 - Maintenance by raising a row of click-fit tiles and a panel of screw-attached osb.

 

6 - Battens screwed to each other rather than to the floor where possible, to avoid more punctures in the air membrane than necessary. 

 

Questions and details:

 

Existing insulation is a filled 50mm cavity, and there will be 100 or 200mm of rockwool under the suspended floor.

 

A - Water pipe penetrations to rad are just a 50mm notch in the floor against the skirting.

 

B - Electric wire runs to sockets at 450mm are normal mini-chases behind skirting boards to be added as decoration. Sockets either sunk-in or surface mount depending.

C - Is it worth putting 25mm insulation into the 63mm deep (CLS on edge) void and the pipes etc on top of that. Can one cable clip or similar to 25mm Celotex? 

 

D - If I am running cables around the void where it is unavoidably against the outside walls, I am thinking I want some insulation against the horizontal cold bridge - eg a 100mm strip of insulation on the outside edge of the void alongside cable runs. Necessary?

 

E - When screwing down battens to the suspended floor is this a place for a blob of silicone on each screw as it is screwed down?

 

Cheers

 

Ferdinand

 

Edited May 1, 2017 by Ferdinand

[Ferdinand]

44 minutes ago, Nickfromwales said:

Now is your most economical opportunity to address these items, so better to spend once now than spend 3-fold later ( and worse if  you have to remove a paying tenant to do so

 

Yep. The target market is either dinky couples, retirees or possibly families with 1-2 children. Lovely street close to a primary school and unusually 3 double bedrooms. Aiming for 5 year tenancies.

 

Ferdinand

 

Edited May 1, 2017 by Ferdinand

[Nickfromwales]

Gas cannot go in an unventilated void unless it is entirely encapsulated in, for eg, dot and dab / bonding compound / similar. The pipe would need taping / sleeving to protect it from any wet product, to prevent corrosion. 

I would recommend taking the gas pipe immediately up to the first floor and running it through the joist space where no such constraint exists. Surface mounted and ( Talon ) trunked for the verticals is easiest. Is the boiler ground or first floor? I'd go externally if ground floor. 

[Ferdinand]

7 minutes ago, Nickfromwales said:

Gas cannot go in an unventilated void unless it is entirely encapsulated in, for eg, dot and dab / bonding compound / similar. The pipe would need taping / sleeving to protect it from any wet product, to prevent corrosion. 

I would recommend taking the gas pipe immediately up to the first floor and running it through the joist space where no such constraint exists. Surface mounted and ( Talon ) trunked for the verticals is easiest. Is the boiler ground or first floor? I'd go externally if ground floor. 

 

It is a bungalow, and I could probably put the boiler within a few feet of the meter box (kitchen cupboard perhaps, or in the hallway). Thanks for the comment.

 

Until I have the gas man in for a quote, I am not sure about the compromise which will be imposed on a small kitchen by modern boiler access space requirements.

Edited May 1, 2017 by Ferdinand

[Nickfromwales]

Download the MI's from your chosen boiler manufacturer and it'll tell you to the mm  

[Nickfromwales]

Ideal logic plus with 7 year warranty is a good rental boiler. My mates fitted scores without issue or recall. 

Its also a 'micro-combi' so smaller box.