70's house renovation

knipex

I have a timber frames house built in 1973 using a Canadian system.

The plasterboard in the house (taped and jointed only) has been damaged (wallpaper removed using steam and the paper surface coming loose in spots causing bubbling) so I am replacing on a room by room basis (DIY as cash becomes available)

Currently the house has no insulation, except for 6" of fibreglass over ceiling (which are foil backed slabs).

4 years ago all windows were replaced with double glazed PVC units

I have stripped the slabs off the walls removed all nails etc and replaced the wiring.

The fame is 4" x 2" battens.

The plan is to insulate between battens with 100mm rockwool (on all walls internal and external to get a fire barrier and to insulate against sound) and then the external walls with 50mm (38mm insulation plus 12mm slab) kingspan insulated slabs.

I have been told that this will eliminate thermal bridging and act as a vapour barrier \ air-barrier.

I will put new 12mm slabs over the existing ceiling slabs laid across existing joints).

Over the next 2 or 3 years the plan is to do all the exact same to all rooms in the house.

The only exceptions being

An en suite extension that was built in the late 80's with hollow block. I will be turning this into a wet-room so the plan is to plaster the wall internally. build a stud frame with 6x2 and insulate with 150mm rockwool. Sheet over with marine ply, then a waterproof liner and tile.

A utility and bathroom extension (which was built 3 years ago built by me and a local handyman when I knew nothing about insulation) and has a 200mm cavity with 50 Styrofoam board. The plan is to blow fill the cavity on this.


Anyone recommend any improvements to this plan.

Once complete I will probably get a BER test completed. What would I need to prove to the tester what has been done (would photographs be sufficient ?)

Viking House

If your timber frame is clad externally in block I would pump the cavity with EPS beads, others here might disagree. The ventilated cavity in timber frame houses was designed to dry any condensation that might occur on the cold side of the timber frame but pumping the cavity will warm up the timbers so no condensation will occur on them.

knipex

It is clad externally (OBS board with tar paper outside) except for under the windows where its just felt.

I talked to a few companies about pumping the cavity and none of them recommended it. In fact one guy refused point blank to even consider doing it.

The condition of the slabs is poor anyway so they have to be replaced one way or another so insulating internally isn't a huge issue.

I did one room last week end. net cost was €350 (plus what ever it costs to get it hardwalled) I also taped the window and spray foamed any gaps after slabbing (around floor and ceiling).

The only issue is that the 2" slab means that the radiator will be mounted 2" further out which means I have to extend the radiator pipes.... Unfortunately I didn't realise until I had the wall slabbed so this weekend I take down that one slab and do the piping (I hate plumbing) and add a TRV.

Viking House

knipex wrote: »

I talked to a few companies about pumping the cavity and none of them recommended it. In fact one guy refused point blank to even consider doing it.

We've been getting that from people for years.
You can't externally Insulate that house! You can't build your house on Polystyrene! You can't plaster directly onto Wood fibre board in this climate!
You can't build single skin! You can't fill the cavities! You can't fill the void under the timber floor with Polystyrene beads, it'll rot the floor! You can't externally insulate Timber Frame houses!

We've done all those things and they work fine, if there's felt on your timber frame it will stop the moisture coming through, the beads won't draw moisture and t'will make it safer from a condensation risk point of view, you're bringing the Dew Point away from the timber frame.

knipex

Viking House wrote: »

We've been getting that from people for years.
You can't externally Insulate that house! You can't build your house on Polystyrene! You can't plaster directly onto Wood fibre board in this climate!
You can't build single skin! You can't fill the cavities! You can't fill the void under the timber floor with Polystyrene beads, it'll rot the floor! You can't externally insulate Timber Frame houses!

We've done all those things and they work fine, if there's felt on your timber frame it will stop the moisture coming through, the beads won't draw moisture and t'will make it safer from a condensation risk point of view, you're bringing the Dew Point away from the timber frame.

So would you advocate bead filling combined with the internal insulation or in-place of ?

Also if there were any tears in the felt would it cause issues ?

Viking House

knipex wrote: »

So would you advocate bead filling combined with the internal insulation or in-place of ? Also if there were any tears in the felt would it cause issues ?

If the rain isn't coming in now then the beads won't pull it in. I would use beads and internally insulate.

sinnerboy

Viking House wrote: »

If your timber frame is clad externally in block I would pump the cavity with EPS beads, others here might disagree. The ventilated cavity in timber frame houses was designed to dry any condensation that might occur on the cold side of the timber frame but pumping the cavity will warm up the timbers so no condensation will occur on them.

It not so simple as that . The external skin of a cavity wall becomes saturated in winter and water can literally flow freely down the hidden face ( the cavity face ) of the external leaf - which is why cavity trays are so vital .

Make no mistake the cavity will be damp .

If the cavity is filled with beads then you may expect that the first ( i.e. that part in contact with the outer leaf ) 5-10mm of the bead fill layer will become saturated.

So think on - liquid water is in itself an very effective vapour barrier . The film of water in the bead layer arising from the external ( rain ) will act as a "stop" the that liquid which arises from the internal - water vapour from the heated internal air . This water source will collect at the coldest point - which will be - the first ( i.e. that part in contact with the outer leaf ) 5-10mm of the bead fill layer ! Water will go forth and multiply .

Consider another factor . Heat transmission through a building fabric is an essential "driver" of water vapour through a building fabric . What if it is not heated ? You go on a winter break - or for some other unforeseen circumstance . Condensation will form in an "earlier" part of the fabric - within the timber frame proper . And without a functioning ventilating cavity - bye bye timber frame .

Viking House

Sorry SB, I don't agree, I remember ringing the test house in the UK about a year ago about the tests they did on the beads for IAB certification, I think it was around Newcastle somewhere, they simulated force 10 wind driven rain using powerhoses on an unplastered block wall with a 100mm bead filled cavity, the rain only ran down the inside of the external blocks, nothing crossed the cavity, not even at 45 degrees, the layer of beads near the wall wasn't wet.

I tested the beads in my shed for capillary pull using a 4 inch pipe filled with beads sitting in a tray of water with holes drilled every 12mm, the holes had pieces of paper in them and were plugged with silicone. I found no capillary pull through the beads.

I poured 1 litre of water into the EPS bead filled pipe and quickly got 1 litre out the other side so they don't hold water. There is still air movement through the beads to aid drying and they won't create a problem in the cavity if there is no problem.

It only rains for 8% of the time in Ireland, I know there are many days with rain but the amount of hours per year that it rains only accounts for 8% of the time and if you wash your floor while it is raining outside it will still dry. If you are worried about your blocks getting wet you could paint them with a waterproofer or paint, this should give you double security.

sinnerboy

The inner face of the outer leaf does run wet in Ireland which is why we must have DPC trays .

Beads will not permit water to pass through them as your own experiments indicate - but I was not suggesting this .

The interface of the external wall leaf and the beads will saturate due to rain penetartion in Winter .
Condensation arising from internal vapour migration will occur at this place too - also during Winter.

At these times the cavity cannot ventilate past this interface which will have in effect created there a vapour barrier formed by the vertical layer of rain penetration and internal vapour condesate .

Respectfully VH - I agree to disagree .

I would never fill the cavity of brick/block faced timber frame .