Dear all,

I've recently built a 44mm thick wood log summer house - one of those
models where the (floating) can be independently fitted inside after
the whole building is erected.

In the standard layout, the structure is designed to stand on a flat
surface such as an even concrete subfloor. Treated floor joists would
then be evenly laid on this subfloor and floarboards would be nailed
to them.

However, as I already had a (sloped) slabbed base, I decided to do
things a bit differently: I built a 100 to 200mmhigh level brick wall
(with one airvent brick every 400mm) and I erected the summer house on
that wall. Now for the suspended floor: the joists are sitting on
pillars 300mm far apart; each is made of one brick (45mm) plus a
suitable length of 75mm treated fence post. Slabs and brickwork are
treated with Hyprufe (a kind of bitumen) to prevent ground dampness to
reach the slabs and then the lower side of the suspended wood fllor
structure. In fact, slabs sit on cement with no damp proof barrier and
in humid and rainy days dampness was very evident even if the whole
area was already inside the floor-less summer house.

By having the slabbed area well sealed, a suspended floor hanging on
the average some 150mm higher, and suitably placed airvent bricks, I
am expecting the resulting cavity to be basically well ventilated and
virtually dry in all weather conditions.

The wood floor structure (joists and battens) is already there and I
am now am planning to install rigid urethane panel cuts between
joists, a damp proof barrier over it, a 18mm thick ply and 18mm floor
boards in this particular order. The Kingspan urethane panels have
some aluminium-like foil on both sides, so they should address heat
loss by radiation. This should allow the floor to be both strong and
well insulated.

However, I am wondering if I am forgetting something essential and/or
doing something wrong, so here I am asking for suggestions/validation/
criticism. Any hint will be appreciated.

Kind regards

W.

Woland wrote:

The wood floor structure (joists and battens) is already there and I
am now am planning to install rigid urethane panel cuts between
joists, a damp proof barrier over it, a 18mm thick ply and 18mm floor
boards in this particular order. The Kingspan urethane panels have
some aluminium-like foil on both sides, so they should address heat
loss by radiation. This should allow the floor to be both strong and
well insulated.

Do you need to cut the urethane panel? You could lay it over the joists,
then ply on top of that.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Woland wrote:


However, I am wondering if I am forgetting something essential and/or
doing something wrong, so here I am asking for suggestions/validation/
criticism. Any hint will be appreciated.


Most certainly you have forgotten a vital thing. Posting photos so we
can all see it. Please. :-)

--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
onset.
Although common it frequently goes undiagnosed.
www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org

wouldnt the kingspan compress where its on the joists,
wouldnt it be better between the plywood and the floorboards?

with the damp-proof plastic on top of the kingspan?

--

[george]



"John Rumm" wrote in message
et...
Woland wrote:

The wood floor structure (joists and battens) is already there and I
am now am planning to install rigid urethane panel cuts between
joists, a damp proof barrier over it, a 18mm thick ply and 18mm floor
boards in this particular order. The Kingspan urethane panels have
some aluminium-like foil on both sides, so they should address heat
loss by radiation. This should allow the floor to be both strong and
well insulated.

Do you need to cut the urethane panel? You could lay it over the joists,
then ply on top of that.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Woland wrote:
Dear all,

I've recently built a 44mm thick wood log summer house - one of those
models where the (floating) can be independently fitted inside after
the whole building is erected.

In the standard layout, the structure is designed to stand on a flat
surface such as an even concrete subfloor. Treated floor joists would
then be evenly laid on this subfloor and floarboards would be nailed
to them.

However, as I already had a (sloped) slabbed base, I decided to do
things a bit differently: I built a 100 to 200mmhigh level brick wall
(with one airvent brick every 400mm) and I erected the summer house on
that wall. Now for the suspended floor: the joists are sitting on
pillars 300mm far apart; each is made of one brick (45mm) plus a
suitable length of 75mm treated fence post. Slabs and brickwork are
treated with Hyprufe (a kind of bitumen) to prevent ground dampness to
reach the slabs and then the lower side of the suspended wood fllor
structure. In fact, slabs sit on cement with no damp proof barrier and
in humid and rainy days dampness was very evident even if the whole
area was already inside the floor-less summer house.

By having the slabbed area well sealed, a suspended floor hanging on
the average some 150mm higher, and suitably placed airvent bricks, I
am expecting the resulting cavity to be basically well ventilated and
virtually dry in all weather conditions.

The wood floor structure (joists and battens) is already there and I
am now am planning to install rigid urethane panel cuts between
joists, a damp proof barrier over it, a 18mm thick ply and 18mm floor
boards in this particular order. The Kingspan urethane panels have
some aluminium-like foil on both sides, so they should address heat
loss by radiation. This should allow the floor to be both strong and
well insulated.

However, I am wondering if I am forgetting something essential and/or
doing something wrong, so here I am asking for suggestions/validation/
criticism. Any hint will be appreciated.


Just two points.

Glue the slabs in place with foaming polyurethane glue to stop them
falling out, and forget the vapor barrier and instead use the aluminium
tape over the slabs AND joists.

Kind regards

W.

George (dicegeorge) wrote:
wouldnt the kingspan compress where its on the joists,

Not especially - it compresses a little when you screw the boards down,
but not much. Pretty much the same construction as a "warm deck" flat roof.

wouldnt it be better between the plywood and the floorboards?

I quite possibly might... the only point I was trying to make was
cutting it in adds lots of work, and means the joists act as thermal
bridges.

with the damp-proof plastic on top of the kingspan?

prolly better under it I would have thought. Having said that, in big
sheets the foil covering will act as a DPC anyway.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Dear all,

thanks for your suggestions and also for the questions that actually
preempted the very same ones.

As requested, here are a couple of photos of the summer house:
http://sites.google.com/site/wolandsworld/

I was thinking of putting a footnote stating that the whole area is
guaranteed and certified 100% tradesman free, but in the end I did not
want to kick-start yet another row with the professional handimen
around...

The first photo in the above web page shows the front (with the air
vents at the bottom); the second one details the suspended floor
structure.

Following John Rumm's suggestion I run a small but convincing
experiment with less than one square foot of Kingspan 50mm thick
urethane board. I basically laid it on a T-shaped part of the wood
floor structure and jumped on it one-footed with the weight of my 80
kgs (yes, I should shed some 10 kgs, but we all enjoy a bit of food &
drink...).
Both the lower and the upper sides of the board chunk showed no sign
of damage or compression!

Another encouraging fact about rigid urethane foam boards is that
Kingspan sell a flooring variant that is basically the same board with
a 18mm chipboard glued on one side (minus the vapour-barrier like
finishing foils).

So, I would say that I will proceed in the following way with John's
suggestion at its co

- Glasswool between the joists, with stapled galvanised chicken wire
to support it (I have the glasswool from a previous extension job)
- Entire Kingspan panels laid on top of the floor structure; no more
need to cut them to pieces (it's a messy job that produces fine dust
and I'm not 100% certain that breathing the stuff - although wearing a
mask - would be without consequences.
- 18 mm ply on top of Kingspan panels. Ply & underlying Kingspan board
can be fixed with thin deck screws as suggested by Kingspan for their
ply-dressed variant
- Possibly thick black polyethylene damp/proof vapour barrier on ply
(provided with the summer house kit, intended to be laid on slabs but
I used Hyprufe aquaseal instead)
- Floorboards on top

Hope it will be ready before the cold weather arrives (I'm in the NE
of Scotland and it won't take too long for temperatures to reach
values below 7C (all paint, glue etc seems not to like lower values).

Cheers

W.

Woland wrote:

Following John Rumm's suggestion I run a small but convincing
experiment with less than one square foot of Kingspan 50mm thick
urethane board. I basically laid it on a T-shaped part of the wood
floor structure and jumped on it one-footed with the weight of my 80
kgs (yes, I should shed some 10 kgs, but we all enjoy a bit of food &
drink...).
Both the lower and the upper sides of the board chunk showed no sign
of damage or compression!

Once you have boards over etc, it ought to be stronger still...

Another encouraging fact about rigid urethane foam boards is that
Kingspan sell a flooring variant that is basically the same board with
a 18mm chipboard glued on one side (minus the vapour-barrier like
finishing foils).

Only thing to watch is cost. Don't know what you need to pay for it with
the chipboard prebonded, but round these parts I can get 50mm insulation
boards at £10/£12 for seconds/new and a couple of sheets of flooring
grade chip at £9 for the pair.

- Glasswool between the joists, with stapled galvanised chicken wire
to support it (I have the glasswool from a previous extension job)

;-) now there is a job I hate! Probably not so bad if you use battens to
fix the wire, otherwise it is a irritating job.

- Entire Kingspan panels laid on top of the floor structure; no more
need to cut them to pieces (it's a messy job that produces fine dust
and I'm not 100% certain that breathing the stuff - although wearing a
mask - would be without consequences.
- 18 mm ply on top of Kingspan panels. Ply & underlying Kingspan board
can be fixed with thin deck screws as suggested by Kingspan for their
ply-dressed variant
- Possibly thick black polyethylene damp/proof vapour barrier on ply
(provided with the summer house kit, intended to be laid on slabs but
I used Hyprufe aquaseal instead)
- Floorboards on top

Are you sure the door will open over that lot?


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Woland wrote:
Dear all,

thanks for your suggestions and also for the questions that actually
preempted the very same ones.

As requested, here are a couple of photos of the summer house:
http://sites.google.com/site/wolandsworld/

I was thinking of putting a footnote stating that the whole area is
guaranteed and certified 100% tradesman free, but in the end I did not
want to kick-start yet another row with the professional handimen
around...

The first photo in the above web page shows the front (with the air
vents at the bottom); the second one details the suspended floor
structure.

Following John Rumm's suggestion I run a small but convincing
experiment with less than one square foot of Kingspan 50mm thick
urethane board. I basically laid it on a T-shaped part of the wood
floor structure and jumped on it one-footed with the weight of my 80
kgs (yes, I should shed some 10 kgs, but we all enjoy a bit of food &
drink...).
Both the lower and the upper sides of the board chunk showed no sign
of damage or compression!

Another encouraging fact about rigid urethane foam boards is that
Kingspan sell a flooring variant that is basically the same board with
a 18mm chipboard glued on one side (minus the vapour-barrier like
finishing foils).

So, I would say that I will proceed in the following way with John's
suggestion at its co

- Glasswool between the joists, with stapled galvanised chicken wire
to support it (I have the glasswool from a previous extension job)
- Entire Kingspan panels laid on top of the floor structure; no more
need to cut them to pieces (it's a messy job that produces fine dust
and I'm not 100% certain that breathing the stuff - although wearing a
mask - would be without consequences.
- 18 mm ply on top of Kingspan panels. Ply & underlying Kingspan board
can be fixed with thin deck screws as suggested by Kingspan for their
ply-dressed variant
- Possibly thick black polyethylene damp/proof vapour barrier on ply
(provided with the summer house kit, intended to be laid on slabs but
I used Hyprufe aquaseal instead)
- Floorboards on top

Hope it will be ready before the cold weather arrives (I'm in the NE
of Scotland and it won't take too long for temperatures to reach
values below 7C (all paint, glue etc seems not to like lower values).


Looks impressively solid. Thanks for posting - it adds a lot to the
description.

--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
onset.
Although common it frequently goes undiagnosed.
www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org

Only thing to watch is cost. Don't know what you need to pay for it
with
the chipboard prebonded, but round these parts I can get 50mm
insulation
boards at £10/£12 for seconds/new and a couple of sheets of flooring
grade chip at £9 for the pair.

- I already have all the insulation boards and the ply. Having
ordered material to insulate floor, walls, and roof one year ago (!)
I got a substantial discount from the timber merchant before prices
started to go up and up and up...

;-) now there is a job I hate! Probably not so bad if you use battens
to
fix the wire, otherwise it is a irritating job.

- I agree, it's not the most enjoyable job to do. However, using the
stapler is not this bad. I am helped by the fact that the fence post
cuts that support the joists & the rest of the floor structure are
wider than the joists themselves, so they provide a minimum of support
for the wire net. Standard rockwool is not very itchy these days...

Are you sure the door will open over that lot?

- Yes, for two reasons. Firstly, the door opens on the outside so
even miscalculations wouldn't have produced any serious practical
effect. However, there is plenty of room as the door threshold level
is some 10 cm above the floor frame level. This is purely accidental
as I had to raise the door frame due to an error that the summer house
kit providers did: the frame was originally 5cm too short to be
aligned with the top of the windows.

Looks impressively solid. Thanks for posting - it adds a lot to the
description.

- Thanks. I spent some time devising that solution and even more
building it. However, it is solid and perfectly dry

Cheers

W.

When I did my last shed I made some panels by gluing 18 mm WBP to
polystyrene to 6mm WBP for the floor.
They are laid on top of joists (18mm on top) and they rest on some concrete
fence posts.
Warm, rigid and not very expensive.