Worth Taking up Chipboard Panels To Make Improvements While the Carpets are off?

[JimbobTheSailor]

Love this forum, I’ve been able to answer so many questions and am really grateful for all the time put into helping complete strangers to learn.

My question is more about whether it’s pointless to attempt this rather than how to do it. My house was built in 2004 at the height of the rush-to-build-to-sell market and isn’t terrible but has issues which I try to resolve when I can.

Background

We’re getting the carpets changed so have an opportunity to get under the floors and:
- Solve severe creaking of many chipboard floor panels.
- Change hanging lights for spotlights in all communal areas except bathroom.
- Reduce ticking sound of some radiator pipes as they expand.
- Lag underfloor heating and hot water pipes (definitely worth it if you can access them).
- Put thermal/sound insulation above ground floor.
- Extend wire-interlinked smoke alarms from communal areas into bedrooms (3-story house so want to be fire extra fire safe).

My main doubt is over the floor panels (2400 x 600 22mm chipboard). They’re lazily installed (gaps filled with carpet offcuts; 2mm of step between corridor and bedrooms; massive amount of levelling cement between top of stairs and adjoining panel about 10mm below; panels not glued/nailed down in many places), and some visibly flex with an 80kg person standing on them (not worryingly, it’s just that you can see it).

Questions

1. Remove ceiling instead? Should I give up on taking up the floor and just pull down the ceilings? Re-installing a ceiling is something I’m less confident about doing so would get in a pro. Non-preferred due to cost and waiting time, but maybe that’s the better choice. Maybe it’s doable to cut lots of small access holes in the ceilling but I feel like the amount of access I need would make it worth removing whole panels.

2. Remove with care? Is it worth the time to take the floor panels out delicately or is it quicker in the long run just to pull off skirting boards and rip up the chipboard?

3. Plywood? This is a question that gets asked a lot but not clear if it’s best for my plans. If I’m going to be taking up floor panels and can do it more quickly by damaging them, should I replace with plywood? Cost isn’t an issue since the ply will cost much less than the carpets and will last much longer, and because I can leave in sity any chipboard that I don't need to get under.
The corridors run parallel to joists so the span between seams only 600mm which creates a lot of of flex points, maybe this issue would still exist in the ply?

4. T&G or butt? I try to avoid anything that's really difficult to disassemble, but I do understand the importance T&G has for rigidity in regions with no support underneath. Is there a way around this? eg. Near walls I could cut the chipboard panel out and router a step into them (to make a butted rabbet joint) - the board by the wall won’t receive weight on it so having a step instead of T&G should be rigid.
Or should I give in and accept that the best floors are T&G then glued and screwed?

Thank you!

 

[blup]

You can assist with rigidity by adding noggins between the joists which also offer additional fixing points if you want to partially replace the floor, and reduces the need for t&g. I only screw not glue the chipboard to make access easier later if needed, though this is not the recommended approach. Getting a smooth continuous surface is important for a smooth carpet so on balance replacement of the whole floor might be the wiser approach

 

[HERTS P&D]

I would pull up the chipboard and insulate between the joists, do any wiring and plumbing, then screw 18mm ply down.

Andy

 

[JohnD]

I would pull up the chipboard and insulate between the joists, do any wiring and plumbing, then screw 18mm ply down.

Andy

100%

Square edge ply you can easily lift by undoing the screws, but support all joints.

While it's up, you can seal any gaps in the ceiling below, insulate pipes, run new cables.

 

[JimbobTheSailor]

Oh great, thanks! That fills me with confidence to get this done.

Is there a drawback in going with 22 m ply instead of 18? Apart from the price. I'm thinking I can save some skirting boards and leave some chipboard in place if I use the same thickness as the current panels.

Could anyone share a best-practice guide for installing square edge plywood?

I've had a look for plywood and am amazed at the number of suppliers and the variety of options. Can anyone recommend a good supplier and / or a type of plywood? I know I need flooring-grade or marine ply but when they start listing the type of wood I get a bit lost.

 

[JohnD]

I used 18mm, and would use 22mm if doing it again.

Measure up the room and use the largest possible pieces with the fewest possible cuts. Put factory edges together because they are straighter and squarer with better corners than your own cuts. Put the whole pieces in the middle of the room and traffic lanes so there will not be much walking over the cut pieces. Put struts ("noggjns") under all unsupported edges. Put your cut edges under skirting. Mark joist positions on the wall to verify your pencil lines for the screws are correct. Stick labels to the wall and marker pen on the flooring to show pipes and cables. You can use paint if they are always going to be covered up. Photograph the subfloor to remind you. Sweep and hoover all the dirt and dust out. There is a slight gap between boards and wall to prevent squeaking. Pack the insulation especially fully round the edges of the room because this is where any dust and draughts will blow up, through the gap under the skirting. Mineral wool is easy to pack tight into irregular gaps. Don't use yellow fibreglass which sheds irritant dust and fibres. The modern soft mineral wool treated with Ecose (it will be marked on the wrapper) is brown and does not shed.

Have some coarse sandpaper handy just in case any of the boards are a tight fit.

I use pink expanding fire foam to seal the plasterboard round the edges of the room and any gaps or cutouts.

You can incorporate hatches for access to pipes, concealed storage, or a floor safe, at edges of the room or behind a door where it will not usually be walked on.

This is a good time to renew the skirting. I can explain the superior method.

 

[opps]

The modern soft mineral wool treated with Ecose (it will be marked on the wrapper) is brown and does not shed.

Didn't know that, tnx.

 

[opps]

I don't think you will need marine ply. Not unless you have a menagerie of incontinent animals.

I have only ever used 18mm for flooring. I can carry a 18mm board, 22mm will be noticeably more heavy. It will also be significantly more expensive because it is less common.

 

[cdbe]

Personally I've always found properly fixed 22mm t&g flooring grade chipboard to be perfectly adequate and a lot easier to use than 8x2 ply.

I doubt you'll get the old stuff up intact (unless it's as inadequately fixed as you say). If the walls are stud work you'll need to watch any that are parallel to the joists. You can reinforce any unsupported joints with 100mm wide strips of chipboard screwed underneath as an alternative to noggins.

Obviously future access is a bit of a pain but not that difficult to cut out neat hatches with a multi tool.

 

[JohnD]

Personally I've always found properly fixed 22mm t&g flooring grade chipboard to be perfectly adequate

Persinally I've always found chipboard is the only flooring that cracks, and that the legs of beds punch through.

 

[JimbobTheSailor]

@JohnD Oh wow that's a really great explanation. Some of the steps I'd planned but at least half were really valuable extra nuggets of info so thank you! The info in your reply would be perfect for a Wiki

Have some coarse sandpaper handy just in case any of the boards are a tight fit.

I'll have an electric planer and electric sander ready as well so if my first cuts are really really bad, I won't have to carry the board back out again.

I use pink expanding fire foam to seal the plasterboard round the edges of the room and any gaps or cutouts.

I have some of the white expanding foam (can't see any mention of fire-resistance), any good or is the main point here the fire resistance?

This is a good time to renew the skirting. I can explain the superior method.

I was very much hoping to avoid this step for any skirting I didn't damage because time is tight, but if you have a pre-written method you can easily share, I'd be happy to learn how.

 

[JimbobTheSailor]

If the walls are stud work you'll need to watch any that are parallel to the joists. You can reinforce any unsupported joints with 100mm wide strips of chipboard screwed underneath as an alternative to noggins.

Thanks, the partition walls are white aerated cement block (Thermalite or similar) with dot & dab plasterboard. I'll be finding out how they're supported this afternoon.
Not a bad idea to reuse the chipboard, are they vertical and are they attached with brackets? I'm not completely confident I could hit the middle of a 22mm board with a screw from the other side of a joist. I guess I could glue 2 or 3 together to make a nice chonky one.

 

[endecotp]

Chipboard and ply aren’t the only options; you could also consider 18mm OSB.

 

[Makeitgo]

Chipboard and ply aren’t the only options; you could also consider 18mm OSB.

Yup, maybe worth looking at the weight and ridgidity of OSB. Apart from its properties when it comes to moisture (if you get the right stuff) I've found OSB lighter and stronger.

 

[JimbobTheSailor]

Bit of a spanner in the works, I've taken the floor up and was met with 80mm of rigid insulation panel (Kingspan), so it's a floating floor, no wonder it creaks so much.

The main surprise is that under the kingspan are heating pipes, and the void for them is made by putting 50mm Kingspan on either side of each pipe, putting a slim piece of wood across them, then putting an upper piece of Kingspan on top. Photo attached.

Under the pipes there are concrete planks supported by a steel I-beam. So looks like the house is more of a chonker than I thought. The floor thickness is 35cm.

So, challenges:
1. What can be done to firm up the floor panels and stop them creaking?
2. Are cables in this kind of ceiling likely to be in conduits only? Any issue with adding cabling without adding the conduit?

----------------------
An aside: I asked ChatGPT to describe the likely make-up of the floor and this is what it came up with:
↑ Upstairs Room Floor
+------------------------+ ← Floor Finish (e.g. laminate, carpet, tiles)
| Screed Layer | ← Sand/cement screed (~50–75mm), or insulation + boards
+------------------------+
|____________________| ← Precast Concrete Planks / Hollowcore Slabs
|____________________| (Laid side-by-side across supporting walls)
+------------------------+
| Suspended Ceiling Void | ← Optional service void (cables, ducts, etc.)
| (if present) |
+------------------------+
| Plasterboard Ceiling | ← Often suspended from concrete using metal framing
+------------------------+
↓ Ground Floor Ceiling