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Have you installed a PIV system? Any good?

I've recently purchased a larger but older (1971) property, with 'sub-optimal' insulation, with the attendant high energy bills and appearance of mould in external wall corners...
IN PLAIN ENGLISH: I've moved into a giant walk-in fridge with some mould thrown in for good measure.

After hearing some horror stories about cavity wall insulation (and seeing some with my own eyes), I've decided to insulate internally with kingspan K17 and 18, rooms are generously sized so can suffer the internal volume loss. I'm also planning to fit felt lap vents in the roof as there is no ventilation there.
The remaining piece of kit to aid ventilation is a PIV, a loft mounted Positive Input Ventilation unit, works on a similar principle to an NBC overpressure system fitted to AFVs. Any of you Arrsers done this, and what we're the results?
 
I've recently purchased a larger but older (1971) property, with 'sub-optimal' insulation, with the attendant high energy bills and appearance of mould in external wall corners...
IN PLAIN ENGLISH: I've moved into a giant walk-in fridge with some mould thrown in for good measure.

After hearing some horror stories about cavity wall insulation (and seeing some with my own eyes), I've decided to insulate internally with kingspan K17 and 18, rooms are generously sized so can suffer the internal volume loss. I'm also planning to fit felt lap vents in the roof as there is no ventilation there.
The remaining piece of kit to aid ventilation is a PIV, a loft mounted Positive Input Ventilation unit, works on a similar principle to an NBC overpressure system fitted to AFVs. Any of you Arrsers done this, and what we're the results?

buy a jumper....
 
Thanks, you've just saved me thousands of pounds. I will buy a jumper and use it wipe your saliva off the inside of your Mum's Transit minibus window.

ETA: I'm not a morning person.
 
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Can’t comment on the PIV bit as a) I've not done it and b) I’ve no idea what one is.

However, I had a similar problem in an old brick house. In one room I stripped off the (3”) plaster back to brick and put in insulation backed plasterboard, put in a new double panel radiator and put down good quality carpet underlay.

It’s now the warmest room in the house by some considerable margin. The board was much cheaper than Kingspan and produced a finishsble surface for plaster skim in one step rather than two. It’s also much thinner (about 80mm) so you won’t lose as much room volume.

In another room I converted essentially an outhouse into a utility room doing what I think you’re proposing to do? The brickwork was so rough that battening it with CLS was the only option to get anything approaching a flat surface for normal board to go onto. I filled the spaces between battens and roof joists with @30mm Kingspan. It improved matters but is nowhere near as warm as the first room.*

* TBF, you can’t really compare them. The utility has two rather than one outside walls, a big towel radiator rather than big double panel, no loft insulation above it and tile on concrete rather than carpet on underlay on wooden floor.
 

neil82

Old-Salt
local housing association fitted loads around here during a round of improvements, most have either had the fuse removed or the wiring cut, turned my flat into an ice box, the only thing I`d like to do with it is shove it *********** of the cnut who decided it was a good idea (and when it was running, still ended up with mould on external walls)
 
To add. A mate has had his house externally clad with insulation. I’ve no idea of the cost but it was reasonably straightforward and has a render applied that he’s painted. It looks good and he reckons it’s hugely improved the heat retention. He got some company or other that specialises in it and it took about 4 days for a good sized semi.

Regarding damp, I’ve used dehumidifiers in the past. The upside is they’re reasonably cheap and extract a staggering amount of water. The downside is they’re ugly, you keep tripping over this box with a wire trailing across the floor, they constantly need emptying and I’m not convinced about their ability to extract water from behind walls etc which will be a longer term and massively expensive problem re rot, mould etc.
 
To add again. In an upstairs shower room in the core of the house (i.e.no external wall) we get a lot of condensation. I’ve installed two fans in the ceiling. Both the actual fan units are in the loft so very quiet with trunking to run the air to/ from the fan unit. One draws air in from the loft so I guess a kind of primitive PIV. The other exhausts air out under the eaves. That and a small free standing dehumidifier seems to have solved the problem? The dehumidifier is about the size of a box of chocolates, small enough to sit on top of the toilet cistern and has a doughnut shaped block in it that needs changing periodically as it erodes away.

Felt flaps can be a ball ache because they flap in wind which is a surprisingly noticeable noise in the dead of night.
 
I've recently purchased a larger but older (1971) property, with 'sub-optimal' insulation, with the attendant high energy bills and appearance of mould in external wall corners...
IN PLAIN ENGLISH: I've moved into a giant walk-in fridge with some mould thrown in for good measure.

After hearing some horror stories about cavity wall insulation (and seeing some with my own eyes), I've decided to insulate internally with kingspan K17 and 18, rooms are generously sized so can suffer the internal volume loss. I'm also planning to fit felt lap vents in the roof as there is no ventilation there.
The remaining piece of kit to aid ventilation is a PIV, a loft mounted Positive Input Ventilation unit, works on a similar principle to an NBC overpressure system fitted to AFVs. Any of you Arrsers done this, and what we're the results?
Just before buying my current place I looked around a place that had one installed. The owner talked us through it, and couldn't be more complimentary of it - he says it sorted the (extensive) black mould problem that he had had incredibly quickly.

I have no reason to doubt him - he was extremely honest about the state of the house (and it was in good nick) and the fact that there were things that may not be uncovered by a survey, but he told us for absolute transparency.
 
local housing association fitted loads around here during a round of improvements, most have either had the fuse removed or the wiring cut, turned my flat into an ice box, the only thing I`d like to do with it is shove it *********** of the cnut who decided it was a good idea (and when it was running, still ended up with mould on external walls)
So you’re not a fan then? (SWIDT?)
 
local housing association fitted loads around here during a round of improvements, most have either had the fuse removed or the wiring cut, turned my flat into an ice box, the only thing I`d like to do with it is shove it *********** of the cnut who decided it was a good idea (and when it was running, still ended up with mould on external walls)
Did u have a facility to adjust the speed?
 

theoriginalphantom

MIA
Book Reviewer
Thanks to this thread I'm looking at getting a system installed
 

skid2

LE
Book Reviewer
Colleague of the dame, big old house, horrible to heat they checked and decided t fill the cavity walls with insulating beads. Chap turns up shoves in hose and away it goes, it’s taking its time on one particular wall.

Then its really taking its time, they shut it off and go for a look. They’ve half filled the basement.
Balls shovelled back into tank and base of wall sealed also resulting in the lack of a stiff breeze blowing through cavity and into the house, even better when refilled with insulation.
 
I've recently purchased a larger but older (1971) property, with 'sub-optimal' insulation, with the attendant high energy bills and appearance of mould in external wall corners...
IN PLAIN ENGLISH: I've moved into a giant walk-in fridge with some mould thrown in for good measure.

After hearing some horror stories about cavity wall insulation (and seeing some with my own eyes), I've decided to insulate internally with kingspan K17 and 18, rooms are generously sized so can suffer the internal volume loss. I'm also planning to fit felt lap vents in the roof as there is no ventilation there.
The remaining piece of kit to aid ventilation is a PIV, a loft mounted Positive Input Ventilation unit, works on a similar principle to an NBC overpressure system fitted to AFVs. Any of you Arrsers done this, and what we're the results?

Spray foam insulation is for winners. By UK standards, our house is pretty substantial, and our ‘leccy bills are ~$180/month, averaged over the year, running two (and sometimes three) A/C systems in the summer. The heating, hot water and stovetop are propane gas, that gets filled every few months, runs about $1500 over the year. If I have my math right, that works out to about £235/mo for both.

I don’t know if you can apply spray foam to masonry cavity walls, I would assume so, but not 100% sure. If not, an inner shell wall of 2 x 4, insulate that, and you’re off to the races. You’d be losing 7” per room. The real biggie is the roof though. Heat rises, exits through the roof. Our garage is NOT spray foam insulated, just fiberglass batts. There is a vast difference In performance. Recent snow took best part of a week to go off the main house roof, the garage (without heating on, just whatever was radiated from the house) was clear within the day.
 
A different perspective.

What about rendering the outside walls. Maybe even pebbledash them. The render should contain a waterproof agent which should stop damp coming through.

That’s not going to make the place warmer but it should cure damp and you can spend some money on heating?

Without knowing more about the building etc, it’s difficult to suggest much else.
 
Hi Rgjbloke, it's not penetrating damp coming through, it's condensation. House is poorly insulated, when you heat it and live in it you produce warm moist air. When that touches ice cold walls it condenses into moisture. Need to raise the temp of the inside face above dew point, hence insulation needed. PIV is claimed to raise air pressure and so encourage it to leak outwards.
 

neil82

Old-Salt
Did u have a facility to adjust the speed?
nope, and they hard-wired it so no option to switch it off when not needed, when they fitted it we got the lecture that it was only going to cost about £6-7 pa to run, what they forgot to mention was the tripling of heating costs, even leaving it off caused cold draughts so now both ceiling vents are blocked off, be very careful and get any promotional B/S in writing
 

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