Worrying noises from loft conversion

[Bert Coules]

A few years ago I had a (timber framed) loft conversion added to my sixties semi-detached bungalow. The ceiling above the rear of the bungalow was completely rebuilt to become also the floor of the major part of the new loft room: timber joists, wet underfloor heating, chipboard top layer, carpet.

For the past month or so I've been hearing worrying sounds coming from this ceiling: sharp cracks, some of which are startlingly loud. They don't appear to emanate from any particular part of the ceiling and sometimes they occur in clusters with each individual sound from a different place. They don't seem to be triggered by any particular circumstances, just occurring at random.

There's been no cracking of the plastered ceiling and as far as I can see, no movement of any of the structure, either in the lower room or the loft extension. But the noises persist. What could be causing them? Could it be the underfloor heating? And whatever the cause, what should I do about it? Any thoughts would be very welcome. Thanks.

[Jack Harry Teesdale]

I would get a building surveyor to take a look at it, it doesn't sound good.

[alan_m]

If it was central heating piping wouldn't it be triggered by the delayed timing of your ch controller?

[Theo]

It could be thermal expansion: if there's a change in temperature, two solid things may have to move past each other to relieve expansion stress - that would cause a nano-earthquake as all the stress is relieved at once, resulting in a snap noise.

Typically this is the cause of pipes creaking when the heating turns on, but it could cause timber-on-timber noises too. With UFH, presumably the entire floor is a central heating pipe, and it could move with respect to the timber structure it sits upon.

I would experiment with the heating controls: what happens if you turn off the UFH completely for a day or two - does it change the frequency of the noises?

Other possibilities: wind loading, structural stresses, failing fixings (nails etc), water leakage...

Theo

[Davey]

..imminent collapse....

[Spike]

Just a thought, but we’ve had some cold North winds recently that have brought low humidity Arctic air. In these circumstances wood can begin to dry out, and make creaking, etc noises. Unfortunately, when normal humidity returns, the process, with noises, is reversed. Our dining-room table seems quite sensitive to this cycle.

[Tim Lamb]

What temperature is the underfloor water? Most designs limit this to

50deg. C but yours may be branched off an existing radiator installation.

[The Natural Philosopher]

I had such over the long hot summer, and I think one part of the house may have subsided about 3mm due to clay shrinkage. After 20 years! one bathroom door doesn't close right and a slight split in nearby tiles has appeared. The cracks are movement of one piece of wood against another.

Its possible that you have very slight structural shifting, or perhaps wood shrinkage due to the low RH inside buildings at this time of year.

Unless you see visible signs of major movement, ignore it

[The Natural Philosopher]

Yes, for the first time in a year, one of my garden doors actually opens and closes freely.

[Brian Gaff]

I suspect something is drying out and warping, so it may be OK now but if it gets worse then something structural may well come loose, assuming no rot oof course There is another thought, Could here be a tiny leak in the heating pips, as this could very quickly dampen timbers and they can rot. This happened to my late uncle in Leads inside an enclosure round some pipes running to the upstairs. He even had fungus inside when the panels were removed. Brian

[Bert Coules]

Many thanks to everyone for the thoughts and suggestions.

Since the sounds have now been going on for eight weeks or so, and given that there's no sign of any movement or cracking, I'd like to think that, whatever's happening, it doesn't indicate a serious structural problem. But of course I could be wrong.

To examine the timber structure of the floor would mean either lifting the upstairs carpet, chipboard, and whatever the heating pipes are laid in (or I suppose they could be clipped to the joists?) or removing the downstairs ceiling. Either way it would be a pretty disruptive job.

There are no radiators, either upstairs or down, and in both zones the wall thermostats are set at 24 degrees. I'll try turning the upstairs one right down and see if that makes any difference.

[Jeff Gaines]

Wow there's a young Swedish activist on her way to beat you over the head. Do you realise your are ruining her childhood :-)

[Bert Coules]

Not that I care in the slightest, but what setting do you think she would suggest?

[Jeff Gaines]

10 in the day and 5 at night :-)

[Bert Coules]

Brian, thanks for the thought. There's been no indication of a leak, though I suppose a very small one might not noticeably affect the pressure indicator on the boiler.

Unfortunately I don't know enough about UFH to know how to check for a leak

[Bert Coules]

At its worse the sound is rather too loud to ignore, I'm afraid.

[Bert Coules]

Hm. Some advice is perhaps best ignored.

[Nick Odell]

I only mean this semi-frivolously but: are you absolutely sure that your delightful next-door neighbours (uk.d-i-y passim) have nothing to do with this?

Nick

[Tim Lamb]

In message [e-mail]>, Bert Coules [e-mail]> writes

Oh. I assumed that the loft conversion heating would be an addition to existing rather than a whole house upgrade.

I installed three different wet underfloor systems here. For solid floors, expanded polystyrene panels with shallow slots for the pipes each having Aluminium foil thermal spreaders. Thin foam sheet to allow movement and then conventional chipboard flooring with very careful nail positioning!

Screeded floor had the pipes clipped to the foam insulation prior to screed laying.

Suspended floor had 18mm pre grooved chipboard laid across the joists with Aluminium grooved spreaders laid in prior to pipe fitting. Foam sheet and chip floor as above.

Two multiway manifolds and circulation pumps controlled by individual roomstats allow local control.

Design pipe spacing and relatively low water temperature (50 C max) make the system slow to respond but fine for geriatric 24 hour occupation.

I can't remember where the idea/need for the 3mm foam isolator came from but retrofit would have been horrendous:-(

>

[Jeff Gaines]

Absolutely, although she may offer to keep you warm at night since I suspect she lacks opportunities in that area.

My programmable hall stat is set at 21 in the day and 16 overnight.