Insulation

[DAPPH]

you will be fine as long as it resmbles this normally the 4" insulation between the ceiling joists is enough for over the first wall
the second roll is rolled out and pushed into the rafters thats more than ample enough

on some you can fit another layer ontop at the edges and it still will allow 1" of air to be in the loft space across the whole roof area its more than enough to allow air flow in the loft as a cold roof method

View attachment 375169

The warmer home grant people surveying our bungalow took one look in my roof void and said it's all got to come out as most of it has turned to dust.
No probs friends did it for me, the under-tile fabric is a non-breathable grey plastic on both sides of a loose woven net.

No way was that going to allow the roof to breathe, so at 1500mm intervals along the seams of the fabric they slid down a flattened spring-loaded diamond of 60 mm or so wide corrugated plastic, this lifted the tiles a fraction and allowed air in or out above the fabric.

I ended up core drilling a six-inch hole at the gable ends, then popped in an air vent cover over them on the outside, slipping & sealing in some 6-inch dia. plastic pipe at each gable end to keep the cavity wall integrity.

Done to get an even better drying air flow as this was the period of longer -term drying the place out after a hidden water leak filled the foundations and came up through the floors & walls ... handy also for air drying our hams and salami

Last time I looked in the roof void it was as dry as a mummified Pharo.

The grant also gave us a 600 mm wide boarded walkway on stand offs to get about 10 mtrs from the trap door down to the solar PV controller that is fitted to one of the gable ends. The new insulation is supposed to have a 30-year warrantee if not walked or covered with boxes etc. directly on the insulation.

 

[Trevorleach]

Do you have a fridge?

I have two dehumidifiiers if that helps

 

[rosinante]

you will be fine as long as it resmbles this normally the 4" insulation between the ceiling joists is enough for over the first wall
the second roll is rolled out and pushed into the rafters thats more than ample enough

on some you can fit another layer ontop at the edges and it still will allow 1" of air to be in the loft space across the whole roof area its more than enough to allow air flow in the loft as a cold roof method

View attachment 375169

That pic explains exactly to me what I am trying to achieve , thank you for that , will use batts only for ease of installation ,
Will leave an air gap , as pic ,
Cheers

 

[rosinante]

As I type this my neighbour is having the cavity wall insulation sucked out of his bungalow and replaced with balls of polystyrene , £4.500 , we will wait to see if the condensation on the west wall stops or diminishes , in the meantime I'll be spending a couple hundred quid on batts to up the eaves insulation .

 

[DAPPH]

As I type this my neighbour is having the cavity wall insulation sucked out of his bungalow and replaced with balls of polystyrene , £4.500 , we will wait to see if the condensation on the west wall stops or diminishes , in the meantime I'll be spending a couple hundred quid on batts to up the eaves insulation .

I thought polystyrene balls were banned because they decompose giving off harmful gasses .

I know of two new builds across the road from where I used to live that were stopped in the mid 1980's , they had to have bottom bricks removed for two courses above th DPC and three bricks in length on the bottom course, a hole every 10 feet or so, so the beads could be vacuumed out & re built then a water resistant rock mineral wool fibre was blown into the cavity between the leaf's . T he BCO forbade them to proceed till he had signed them off as being done .

Once we had our bungalow's outside walls sprayed in a plastic sealer paint colour a lot of the dampness stopped

 

[rosinante]

3 weeks ago I formed a recess for a tv in a customer house , the construction was a cavity wall with no insulation , internally the wall has 50mm stud with 50mm polystyrene board between with a polythene vapour barrier on the warm side , that surprised me, house built in the 90s, 4 beds in an expensive postcode. Imagine also look into external cladding insulation ,

 

[Shox Dr]

Thermal imaging cameras are the way to find heat loss. My son has just spent 35quid heating his ex-council 1960 semi for 4 days to 18c. I went round with the camera. Could not believe the heat bleeding out the walls.
This is his gable end


The front.


No insulation in the cavity at all.
Compaired to ours, I extended it 20yrs ago. Made sure everywhere was really well insulated.

 

[Shox Dr]

I bit more info on the post above. The Hot spot in the bottom left corner is the Dog. Top right of middle is a light in the room.

Not happy with the loss out the windows. the glazing was replaced 4yrs ago with all singing all dancing glass Pillkington ISTR ( an additional cost). No damn difference to the 20yr first fit, though it had to be done the seals had failed. The thin horizontal line is a clear uPVC roof partly over the livingroom. There's a 7' Double rad under the window, still cant melt snow on the roof. Blurb said it had better insulation then a 9" Insulated cavity wall.

 

[Trevorleach]

I bit more info on the post above. The Hot spot in the bottom left corner is the Dog. Top right of middle is a light in the room.

Not happy with the loss out the windows. the glazing was replaced 4yrs ago with all singing all dancing glass Pillkington ISTR ( an additional cost). No damn difference to the 20yr first fit, though it had to be done the seals had failed. The thin horizontal line is a clear uPVC roof partly over the livingroom. There's a 7' Double rad under the window, still cant melt snow on the roof. Blurb said it had better insulation then a 9" Insulated cavity wall.

Temp in living room today between 14 and 16 degc c, gas bill for the day so far 5.38!
Std cavity walls with blown fibre insulation, triple glazed windows 6 years old, extra loft insulation and under tile between rafters celotex insulation.

 

[Pigeon_Droppings2]

10+ years ago when we did our refurb we insulated the wood floors with kingspan....that made a massive difference as I recall.

The blown fibre for cavity sounds interesting....I'll have to look into that.

 

[DAPPH]

The latest blown fibre should be water resisting and have a 20yr warrantee .

Be aware of cowboys & con men saying they'll do cavity wall insulation for you if you have the old 9 inch solid brick walls that don't have a cavity

In 1989 I got my house done for 2/3 of the lowest quote simply by by riding around to find a contractor doing council work blown insulation , talked to the boss man , they were only too happy to do our three bed ex council house's external walls .

It took them about 3/4 of an hour at the end of their normal day . I got a receipt there & then and a warrantee certificate posted to me a few days later .. very handy when we sold the place .

Three of them arrived in a stretch Luton towing a Broom and Wade air compressor for the star drill , inside the stretch was their bale shredding machine , several bales of compressed fibre and the blowing machine plus numerous lengths of armoured hose to transport the blown fibres to a cone nozzle fitted with a pressure gauge.

Those three guys had it down to a " T " . one drilled the holes at ground level, one started blowing the fibres in whilst the other fed the shredder in the truck. The guy doing the drilling was up on a ladder doing the next level of holes and almost finished on the row when the filler guy got on another ladder and started blowing in fibre behind him .

Top row was done the same , then they vacuumed up the star drilled mortar dust , mixed it up with some sand and cement and filled in all the access holes in the mortar work which they'd drilled out .
When it was all dry it was difficult to see where they had been drilling.


That winter it was truly amazing to see ice on our outside walls and non on the semi attached to ours or on other uninsulated houses down the street .

Our heating bills dropped humongously after I put the roof void insulation in myself, using a long handle T bar to push rolled up rock mineral wool insulation out to the eves but not right hard into them, as you still need some air flow in the roof void.
I put three thickness in the void , in grid over laps, much more depth and there would be sweating & mould problems from room absorbed moisture within the plaster board ceilings .

Found out a few week later that they would have put blown fibre in the roof void too had I asked them, for another £60 .