Have chosen engineered wood flooring to fit over my UFH. As I
understand it I have 3 (or maybe 4) choices of how to fit, and am
interested in views on benefits/drawbacks of each.

1) Glue direct to concrete screed.

2) Fix (nail) to battens fitted into concrete.

3) Fix (nail) to joists, fitted periodically within concrete screed
(perhaps every metre).

4) Leave floating (on top of underlay).

In some ways, 4 seems like the best on the basis that
- it's easier
- as and when there's any shrinkage I can simply push the boards
together again.
However, I worry a bit about how bouncy it might be.

By the way, should I avoid engineered flooring using pine underneath
the "veneer", and prefer plywood - I've seen reports that plywood is a
better material to be using as there's less shrinkage (the main reason
for using engineered).

Thanks,
Piers

wrote:

Have chosen engineered wood flooring to fit over my UFH. As I
understand it I have 3 (or maybe 4) choices of how to fit, and am
interested in views on benefits/drawbacks of each.

1) Glue direct to concrete screed.

2) Fix (nail) to battens fitted into concrete.

3) Fix (nail) to joists, fitted periodically within concrete screed
(perhaps every metre).

4) Leave floating (on top of underlay).

In some ways, 4 seems like the best on the basis that
- it's easier
- as and when there's any shrinkage I can simply push the boards
together again.
However, I worry a bit about how bouncy it might be.

By the way, should I avoid engineered flooring using pine underneath
the "veneer", and prefer plywood - I've seen reports that plywood is a
better material to be using as there's less shrinkage (the main reason
for using engineered).

Thanks,
Piers

I floated mine, and it seemed a good approach. But then mine was designed
solely for floated installation, so I didn't have much choice anyway.

Benefits:

1) You'll lay on a foam underlay which a) may (should ideally) contain a DPM
layer which is belt and braces; b) allow a bit for any imperfections in the
flatness of the concrete.

2) Is easier;

3) Can be lifted for repair (unlikely but at least you have the option),
assuming dry fit click-lok type

4) If your subfloor is not insulated, lob 12mm marmox down first and screw
that to the screed with stainless screws. For a very small loss of height,
12mm makes a huge improvement when you have a freezing cold slab underneath.

As for the foam, I used Tredaire (sp?) Boardwalk. Pretty decent stuff.


Cheers

Tim
--
Tim Watts

On 18/10/2011 21:32, Tim Watts wrote:


I floated mine, and it seemed a good approach. But then mine was designed
solely for floated installation, so I didn't have much choice anyway.

Benefits:

1) You'll lay on a foam underlay which a) may (should ideally) contain a DPM
layer which is belt and braces; b) allow a bit for any imperfections in the
flatness of the concrete.

2) Is easier;

3) Can be lifted for repair (unlikely but at least you have the option),
assuming dry fit click-lok type

4) If your subfloor is not insulated, lob 12mm marmox down first and screw
that to the screed with stainless screws. For a very small loss of height,
12mm makes a huge improvement when you have a freezing cold slab underneath.

As for the foam, I used Tredaire (sp?) Boardwalk. Pretty decent stuff.


Cheers

Tim

You seem to be overlooking the fact that this flooring will have UFH
under it - although the OP doesn't say whether it's wet or electric.

Either way, the foam slab needs to go *under* the heating system so that
the heat can rise but not go into the ground.

If the floor doesn't need to float - which most engineered wood floors
I've come across *do* - gluing it to the screed with a suitable adhesive
for use over UFH would be the best bet.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On 18/10/2011 20:48, Piers Finlayson wrote:
Have chosen engineered wood flooring to fit over my UFH. As I understand
it I have 3 (or maybe 4) choices of how to fit, and am interested in
views on benefits/drawbacks of each.

1) Glue direct to concrete screed.

2) Fix (nail) to battens fitted into concrete.

3) Fix (nail) to joists, fitted periodically within concrete screed
(perhaps every metre).

4) Leave floating (on top of underlay).

In some ways, 4 seems like the best on the basis that
- it's easier
- as and when there's any shrinkage I can simply push the boards
together again.
However, I worry a bit about how bouncy it might be.

4 is the most common way, and its unlikely to bounce unless the floor is
very uneven. 2 is the way to go if the floor is very unlevel and needs
flattening. If the boards are glued together, they won't pull apart.

By the way, should I avoid engineered flooring using pine underneath the
"veneer", and prefer plywood - I've seen reports that plywood is a
better material to be using as there's less shrinkage (the main reason
for using engineered).

Ply or MDF are the most common because the substrate is seasonally stable.



--
Cheers,

John.

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

Roger Mills wrote:

On 18/10/2011 21:32, Tim Watts wrote:


I floated mine, and it seemed a good approach. But then mine was designed
solely for floated installation, so I didn't have much choice anyway.

Benefits:

1) You'll lay on a foam underlay which a) may (should ideally) contain a
DPM layer which is belt and braces; b) allow a bit for any imperfections
in the flatness of the concrete.

2) Is easier;

3) Can be lifted for repair (unlikely but at least you have the option),
assuming dry fit click-lok type

4) If your subfloor is not insulated, lob 12mm marmox down first and
screw that to the screed with stainless screws. For a very small loss of
height, 12mm makes a huge improvement when you have a freezing cold slab
underneath.

As for the foam, I used Tredaire (sp?) Boardwalk. Pretty decent stuff.


Cheers

Tim

You seem to be overlooking the fact that this flooring will have UFH
under it - although the OP doesn't say whether it's wet or electric.

Either way, the foam slab needs to go *under* the heating system so that
the heat can rise but not go into the ground.

If the floor doesn't need to float - which most engineered wood floors
I've come across *do* - gluing it to the screed with a suitable adhesive
for use over UFH would be the best bet.

Oh - didn't see that bit... I'm sure some of the underlays are rated for UFH
use though; seem to remember that when I was looking for mine.

--
Tim Watts

On 18/10/11 20:48, Piers Finlayson wrote:
Have chosen engineered wood flooring to fit over my UFH. As I understand
it I have 3 (or maybe 4) choices of how to fit, and am interested in
views on benefits/drawbacks of each.

1) Glue direct to concrete screed.

This is what I have had done, as I don't like bouncy wooden floors - I'm
16 stone, so floating floors tend to depress quite a bit when I walk on
them, I suspect the effect is less noticeable to lighter people. Before
gluing the boards, my concrete floor was painted with a thick coating of
epoxy sealant, mitigation against any current or future problem with the
DPM, but since you have UFH this is probably not necessary.

2) Fix (nail) to battens fitted into concrete.

3) Fix (nail) to joists, fitted periodically within concrete screed
(perhaps every metre).

4) Leave floating (on top of underlay).

Underlay will surely insulate you from the UFH - unless perhaps there is
underlay specifically designed for this usage.


In some ways, 4 seems like the best on the basis that
- it's easier
- as and when there's any shrinkage I can simply push the boards
together again.
However, I worry a bit about how bouncy it might be.

By the way, should I avoid engineered flooring using pine underneath the
"veneer", and prefer plywood - I've seen reports that plywood is a
better material to be using as there's less shrinkage (the main reason
for using engineered).

Yes, ply will be much more stable in the long term.

On 2011-10-18 20:48:59 +0100, Piers Finlayson said:

Have chosen engineered wood flooring to fit over my UFH. As I
understand it I have 3 (or maybe 4) choices of how to fit, and am
interested in views on benefits/drawbacks of each.

1) Glue direct to concrete screed.

2) Fix (nail) to battens fitted into concrete.

3) Fix (nail) to joists, fitted periodically within concrete screed
(perhaps every metre).

4) Leave floating (on top of underlay).

In some ways, 4 seems like the best on the basis that
- it's easier
- as and when there's any shrinkage I can simply push the boards
together again.
However, I worry a bit about how bouncy it might be.

By the way, should I avoid engineered flooring using pine underneath
the "veneer", and prefer plywood - I've seen reports that plywood is a
better material to be using as there's less shrinkage (the main reason
for using engineered).

Thanks all. As the screed hasn't gone down yet, I'll make sure it gets
done very well (level) and probably leave floating, at least initially,
ensuring there's no bouncing.

Another question. At one end of the room I'll be having a wood burning
stove. (More for aethetics than to usefully heat.) I will be setting
a stone hearth directly onto the concrete on which to sit this stove.
What's the best way to terminate the wood floor against this hearth? I
don't really want to leave a gap and then beading, cos I think it looks
crap. But, presumably I can't just butt up against the hearth because
then the floor might expand and warp. Is allowing the woodd floor to
slide under the front of the hearth sensible?

Thanks,
Piers

wrote:


Another question. At one end of the room I'll be having a wood burning
stove. (More for aethetics than to usefully heat.) I will be setting
a stone hearth directly onto the concrete on which to sit this stove.
What's the best way to terminate the wood floor against this hearth? I
don't really want to leave a gap and then beading, cos I think it looks
crap. But, presumably I can't just butt up against the hearth because
then the floor might expand and warp. Is allowing the woodd floor to
slide under the front of the hearth sensible?

Thanks,
Piers

L-shaped infill strip that drops in the gap and has a thin bevelled piece
the covers the gap and overlaps the wood by about 10mm. Glue lightly to the
hearth edge so the wood and slide underneath it and maintain the expansion
gap.

--
Tim Watts

Piers Finlayson wrote:
On 2011-10-18 20:48:59 +0100, Piers Finlayson said:

Have chosen engineered wood flooring to fit over my UFH. As I
understand it I have 3 (or maybe 4) choices of how to fit, and am
interested in views on benefits/drawbacks of each.

1) Glue direct to concrete screed.

2) Fix (nail) to battens fitted into concrete.

3) Fix (nail) to joists, fitted periodically within concrete screed
(perhaps every metre).

4) Leave floating (on top of underlay).

In some ways, 4 seems like the best on the basis that
- it's easier
- as and when there's any shrinkage I can simply push the boards
together again.
However, I worry a bit about how bouncy it might be.

By the way, should I avoid engineered flooring using pine underneath
the "veneer", and prefer plywood - I've seen reports that plywood is a
better material to be using as there's less shrinkage (the main reason
for using engineered).

Thanks all. As the screed hasn't gone down yet, I'll make sure it gets
done very well (level) and probably leave floating, at least initially,
ensuring there's no bouncing.

Another question. At one end of the room I'll be having a wood burning
stove. (More for aethetics than to usefully heat.) I will be setting a
stone hearth directly onto the concrete on which to sit this stove.
What's the best way to terminate the wood floor against this hearth? I
don't really want to leave a gap and then beading, cos I think it looks
crap. But, presumably I can't just butt up against the hearth because
then the floor might expand and warp. Is allowing the woodd floor to
slide under the front of the hearth sensible?


What I did was simply leave a small gap. If its engineering the
expansion is low - so probably a couple of mm is enough to stop it
bowing upwards. Or you can use a cork edge strip. Or you can glue
beading to the hearth for a sliding fit over the floor Or use a
flexible mastic caulk..

Thanks,
Piers

On Wed, 19 Oct 2011 19:13:31 +0100, Piers Finlayson wrote:
Is allowing the woodd floor to
slide under the front of the hearth sensible?

If the hearth's tall enough to allow it I'd say yes - put a small lip in
the leading edge and let the wood floor slide under it. As TNP says, it's
likely only a matter of a couple of mm.

cheers

Jules

Jules Richardson wrote:

On Wed, 19 Oct 2011 19:13:31 +0100, Piers Finlayson wrote:
Is allowing the woodd floor to
slide under the front of the hearth sensible?

If the hearth's tall enough to allow it I'd say yes - put a small lip in
the leading edge and let the wood floor slide under it. As TNP says, it's
likely only a matter of a couple of mm.

cheers

Jules

It's typically 5-10mm depending on the dimensions of the room, based on the
data sheet I followed (Kahrs). For most average to smaller rooms, 5mm all
round is a sensible number.

--
Tim Watts

On 20/10/2011 01:13, Tim Watts wrote:
Jules Richardson wrote:

On Wed, 19 Oct 2011 19:13:31 +0100, Piers Finlayson wrote:
Is allowing the woodd floor to
slide under the front of the hearth sensible?

If the hearth's tall enough to allow it I'd say yes - put a small lip in
the leading edge and let the wood floor slide under it. As TNP says, it's
likely only a matter of a couple of mm.

cheers

Jules

It's typically 5-10mm depending on the dimensions of the room, based on the
data sheet I followed (Kahrs). For most average to smaller rooms, 5mm all
round is a sensible number.

The instructions for these types of flooring always annoy me -
specifying fixed gaps without taking any account of the actual room
dimensions! How difficult would it be to say "leave n mm gap for each
metre of room length"?


--
Cheers,

John.

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

On 20/10/2011 2:40 p.m., John Rumm wrote:

It's typically 5-10mm depending on the dimensions of the room, based
on the
data sheet I followed (Kahrs). For most average to smaller rooms, 5mm all
round is a sensible number.

The instructions for these types of flooring always annoy me -
specifying fixed gaps without taking any account of the actual room
dimensions! How difficult would it be to say "leave n mm gap for each
metre of room length"?



When I was talking to different contractors about getting a
tongue-in-groove wood floor installed over chipboard, some of them
claimed it was necessary to leave up to 10mm gap at the walls. This
made no sense to me, since the floor was to be glued down. In the
event, the installer I chose laid the wood so it butted snugly up
against the walls. That was a couple of years ago, and there is no sign
of any problem - no apparent movement. This doesn't surprise me, since
I know the adhesive used is very strong.

Tim Watts wrote:
Jules Richardson wrote:

On Wed, 19 Oct 2011 19:13:31 +0100, Piers Finlayson wrote:
Is allowing the woodd floor to
slide under the front of the hearth sensible?
If the hearth's tall enough to allow it I'd say yes - put a small lip in
the leading edge and let the wood floor slide under it. As TNP says, it's
likely only a matter of a couple of mm.

cheers

Jules

It's typically 5-10mm depending on the dimensions of the room, based on the
data sheet I followed (Kahrs). For most average to smaller rooms, 5mm all
round is a sensible number.

I got away with less than 5mm over a 15 meter wide room (Kahrs)

The material itself makes a reasonable amount of compression before it
buckles.

Its worst in summer, when air is not heated and humidity is as high as
outside: In winter with UFH the floor gets very dry indeed. If laying
about now leave 5mm gap and relieve in summer ONLY if you experience issues.

John Rumm wrote:
On 20/10/2011 01:13, Tim Watts wrote:
Jules Richardson wrote:

On Wed, 19 Oct 2011 19:13:31 +0100, Piers Finlayson wrote:
Is allowing the woodd floor to
slide under the front of the hearth sensible?

If the hearth's tall enough to allow it I'd say yes - put a small lip in
the leading edge and let the wood floor slide under it. As TNP says,
it's
likely only a matter of a couple of mm.

cheers

Jules

It's typically 5-10mm depending on the dimensions of the room, based
on the
data sheet I followed (Kahrs). For most average to smaller rooms, 5mm all
round is a sensible number.

The instructions for these types of flooring always annoy me -
specifying fixed gaps without taking any account of the actual room
dimensions! How difficult would it be to say "leave n mm gap for each
metre of room length"?


Also it expands more across the board than along it, sligthly.

BUT the joints will also allow some movement laterally.

I'd allow 1mm per meter myself give or take.

Its not possible to say how humid your room might get in summer, either.

Gib Bogle wrote:
On 20/10/2011 2:40 p.m., John Rumm wrote:

It's typically 5-10mm depending on the dimensions of the room, based
on the
data sheet I followed (Kahrs). For most average to smaller rooms, 5mm
all
round is a sensible number.

The instructions for these types of flooring always annoy me -
specifying fixed gaps without taking any account of the actual room
dimensions! How difficult would it be to say "leave n mm gap for each
metre of room length"?



When I was talking to different contractors about getting a
tongue-in-groove wood floor installed over chipboard, some of them
claimed it was necessary to leave up to 10mm gap at the walls. This
made no sense to me, since the floor was to be glued down. In the
event, the installer I chose laid the wood so it butted snugly up
against the walls. That was a couple of years ago, and there is no sign
of any problem - no apparent movement. This doesn't surprise me, since
I know the adhesive used is very strong.

Yes. I laid floating and all that happened with no gap was the floor got
a bit hollow - buckled up SLIGHTLY - at one point. Standing on it made
it go back down. Glue would have held it no problems


Its the same principle as long welded rails with no expansion joints:
Provided its laid with heavy concrete sleepers that wont allow buckling,
it just goes into compression when it expands, so to speak.

On Thu, 20 Oct 2011 02:40:08 +0100, John Rumm wrote:

On 20/10/2011 01:13, Tim Watts wrote:
Jules Richardson wrote:

On Wed, 19 Oct 2011 19:13:31 +0100, Piers Finlayson wrote:
Is allowing the woodd floor to
slide under the front of the hearth sensible?

If the hearth's tall enough to allow it I'd say yes - put a small lip
in the leading edge and let the wood floor slide under it. As TNP
says, it's likely only a matter of a couple of mm.

cheers

Jules

It's typically 5-10mm depending on the dimensions of the room, based on
the data sheet I followed (Kahrs). For most average to smaller rooms,
5mm all round is a sensible number.

Hmm, maybe it's more for the engineered stuff. Ours are all 3/4"-high oak
(1-1/2" wide strips) and the longest span (but that's along the grain,
not across) is somewhere around 50 feet - my gut feeling is that the
expansion really isn't much at all, though. (maybe I should measure it,
but of course that's a long term project :-)

If the hearth is tall enough I think it'd be possible to take 7mm (say)
out of it for the gap, anyway. (Do the boards, when delivered, come with
a guarantee that they've have been stored such that they're close to
their smallest size? Otherwise I don't see how anyone can engineer the
expansion gaps to the right size - it'd be a bugger to lay it with a 5mm
gap all around, only to find that the gap opens to 10mm because the
boards were delivered at their biggest size!)

cheers

Jules

Jules Richardson wrote:

On Thu, 20 Oct 2011 02:40:08 +0100, John Rumm wrote:

On 20/10/2011 01:13, Tim Watts wrote:
Jules Richardson wrote:

On Wed, 19 Oct 2011 19:13:31 +0100, Piers Finlayson wrote:
Is allowing the woodd floor to
slide under the front of the hearth sensible?

If the hearth's tall enough to allow it I'd say yes - put a small lip
in the leading edge and let the wood floor slide under it. As TNP
says, it's likely only a matter of a couple of mm.

cheers

Jules

It's typically 5-10mm depending on the dimensions of the room, based on
the data sheet I followed (Kahrs). For most average to smaller rooms,
5mm all round is a sensible number.

Hmm, maybe it's more for the engineered stuff. Ours are all 3/4"-high oak
(1-1/2" wide strips) and the longest span (but that's along the grain,
not across) is somewhere around 50 feet - my gut feeling is that the
expansion really isn't much at all, though. (maybe I should measure it,
but of course that's a long term project :-)

If the hearth is tall enough I think it'd be possible to take 7mm (say)
out of it for the gap, anyway. (Do the boards, when delivered, come with
a guarantee that they've have been stored such that they're close to
their smallest size?


No - it's entirely dependent on temperature and humidity.

Otherwise I don't see how anyone can engineer the
expansion gaps to the right size - it'd be a bugger to lay it with a 5mm
gap all around, only to find that the gap opens to 10mm because the
boards were delivered at their biggest size!)

I think that quoted gaps are "worst case". I've not noticed much variation
with mine where I can still see the cut edge by a door (sans architrave).

I guarantee if they were fitted wedged tight in, then you'd have a problem
(as TMH IIRC can attest to - I recall he had to fix one such case for
someone).

However, if you leave 5mm all round, unless the room is massive, you'd be
pretty safe.


--
Tim Watts

On 2011-10-20 08:38:19 +0100, The Natural Philosopher said:

Tim Watts wrote:
Jules Richardson wrote:

On Wed, 19 Oct 2011 19:13:31 +0100, Piers Finlayson wrote:
Is allowing the woodd floor to
slide under the front of the hearth sensible?
If the hearth's tall enough to allow it I'd say yes - put a small lip in
the leading edge and let the wood floor slide under it. As TNP says, it's
likely only a matter of a couple of mm.

cheers

Jules

It's typically 5-10mm depending on the dimensions of the room, based on
the data sheet I followed (Kahrs). For most average to smaller rooms,
5mm all round is a sensible number.

I got away with less than 5mm over a 15 meter wide room (Kahrs)

The material itself makes a reasonable amount of compression before it buckles.

Its worst in summer, when air is not heated and humidity is as high as
outside: In winter with UFH the floor gets very dry indeed. If laying
about now leave 5mm gap and relieve in summer ONLY if you experience
issues.

It's a big room - 11m long (in the direction I'm worrying about here),
so I do need to leave a gap.

On Wed, 19 Oct 2011 19:13:31 +0100, Piers Finlayson wrote:

Another question. At one end of the room I'll be having a wood burning
stove. (More for aethetics than to usefully heat.)

Even a tiny small stove will kick out over a kW of heat. In a normal
sized, insulated room, that is more than enough...

I will be setting a stone hearth directly onto the concrete on which to
sit this stove. What's the best way to terminate the wood floor against
this hearth?

One assumes that the stone will be bedded on some mortar? Arrange the
thickness of that to allow the flooring to slip under the stone.

--
Cheers
Dave.