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Author Topic: Sanity check for Insulating a house  (Read 2684 times)
NugentS
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« on: June 14, 2019, 11:39:10 AM »

Hi All,

I have a 4 bedroom end terrace house built I guess 60's/70's (2 bedrooms could be described as cat unfriendly when swinging said feline)
The loft is boarded with fibreglass of some make - however I have discovered that this is largely degraded having been installed 15+ years ago. I use the roof space for storing boxes of stuff I might need later
The rafters are not insulated. The roof is a normal tile roof on a felt membrane (damaged in two places one on each side). No leaks
I have solar panels on one side of the roof
External walls are cavity and filled with some sort of wool like material - again 15+ years ago
Internal walls are stud / plasterboard
Windows are all uPVC double glazing with vents in almost all cases
I have no mold problems that I have spotted
Downstairs is a suspended wooden floor, part of which is carpeted, part of which is vinyl (kitchen) and part of which has some sort of green board stuff covered by fake wood paneling.
The floor is suspended - there is no insulation below the floor - which is just an open space (effectively) .
Boiler is Gas, quite new. Central heating (rads) + air con for some rooms.
I have an intelligent heating system (Heat Genius) that covers most rooms

Top floor is quite warm thus air con units for when it gets really warm. Ground floor is always much colder. I know heat rises but heating downstairs is harder than upstairs. I have plenty of passive heating upstairs (computers etc on 24*7) so some rooms never get heated

My thoughts.
The gable ends need repointing internally
Use an open cell foam (Icynene - I don't know if there are others) to cover the rafters and gable ends
Use the same foam under the ground floor to insulate there as well.

Does this seem sensible?

Any other ideas, thoughts, suggestions.

Sean




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Countrypaul
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« Reply #1 on: June 14, 2019, 12:17:15 PM »

About 15 years ago I was involved in renovating a listed (2) Georgian house that was used for offices. The roof was slate tiles with a somewhat tired sarking and no insulation, just boards fastened to the beams, several tiles were damaged/missing. It was debated whether to completely redo the roof or repair it instead. In the end the missing and broken tiles were replaced and the tired sarking removed from the inside. In order to insulate the roof, and try to prevent any tile movement, it was decided to spray foam the whole underside of the roof, not sure if this was only to the depth of the rafters or slightly more. There was no heating in the building at the time and the spraying was done at the end of the week. Come monday the builders could immediately notice the whole building was much warmer.

I know Icynene was looked at, but in the end they went with PUR/PIR.

In our house which we renovated, the architect had suggested using Icynene to insulate the ground floor from below once the various parts had been done. As we went through looking at each room we came to the conclusion that more than 50% of the floor would be new and that would be beam and block with UFH. It left some rooms having a combination of new B&B floor with UFH and suspended wooden floor with large amounts of patches. The joists for the wooden floor were only 4x2 and therefore extra dwarf walls had been added underneath (without any foundations) at 5ft and 10ft along (15ft beams). The eventual conclusion was that the cost of putting B&B floor throughout the ground floor was not significantly more than trying to make do with the existing floor with Icynene sprayed on from below.  Given that the mixed floor would have been noticable and restricted the use of UFH we decided that  putting a B&B floor in throughout made most sense and reduced the risk of future problems.
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pantsmachine
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« Reply #2 on: June 14, 2019, 12:54:08 PM »

Couple off the top of my head from my own insulation adventures. Check how your loft space is ventilated and if you spray foam ensure it remains vented. Same with underfloor. On the central heating system. Ensure it is balanced and rads spec'd properly for room size. Begin a uncontrolled air leak search. That in itself makes a large difference. I look forward to reading your findings and progress.
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brackwell
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« Reply #3 on: June 14, 2019, 01:34:25 PM »

When the calculations of heat loss from houses is done by far the largest influence is that of exterior air flow and this is where you should start if not already. Block up and preferably remove open chimneys,pay attention to other air extractors and close those trickle air vents, seal under skirting boads that leave a gap,seal floor board gaps,around pipe holes etc. Go around the house on a windy day holding your hand up to possible draughty places.

I trust your gas boiler is of a balanced flue type and does not have the oblgatory air vent required for non balanced flue.

Stopping draughts will do more than anything else you are proposing but have a plan for controlling any excess humidity like showers or drying clothes indoors etc.  Dont worry it is impossible nearly to make old house so air tight as to cause problems but keep an eye out for it.

Next, In the loft you need to aim for approaching 300mm of fluffy stuff or equivalent. This can be easily achieved on the non boarded part but may mean reboarding/raising.

Because every little helps there is benefit in preventing the underfloor venting air (necassary) getting to the underside of the floor boards and how you do this really depends on underfloor depth and skill levels.

I wonder if some of the topwarm/bottom cold is due to open planning and air free to move up the stairs.  If you were really keen you might do something about addressing this issue.

Ken

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RIT
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« Reply #4 on: June 14, 2019, 01:40:50 PM »

In terms of dealing with the loft, look up 'loft stilts' on google.

These are great for raising the loft boards you have to provide box storage so that you have space underneath for the correct amount of installation. I installed mine with loose fill insulation, which greatly simplified the process.

Once you have 270mm of installation in place the need to insulate the roof will drop in terms of its priority.
« Last Edit: June 14, 2019, 01:47:53 PM by RIT » Logged

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dimengineer
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« Reply #5 on: June 14, 2019, 03:33:29 PM »

Just be a bit careful about condensation.
I've a 1920 detached house with cavities.

Done most things - DG, Cavity Insulation, Loft insulation, Draught proofing

We are right on the edge of condensation & mould problems and have to manage it quite carefully. The tipping point was the cavity insulation which of course reduced a lot of the tramp ventilation through the walls. We have one room which has single skin 1970's extension which has to be watched very carefully. Its the cold spot in the house, and with minimal ventilation, we can get problems.

Just my tuppence worht

Dehumidifiers are great!
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pantsmachine
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« Reply #6 on: June 14, 2019, 03:52:27 PM »

Dimeng, for your worst room. https://www.condensationproducts.co.uk/product/anti-mould-paint-protection-additive/

We have a number of rental houses and I swear by this stuff.
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HUGE insulation depth.
5.12 kw PV system with Solar edge.
4.8 kw Pylon tech battery storage.
All Low energy bulbs.
Solar I boost charging 210 ltr OSO system tank.
Balanced & zoned CH wet system & Hive 2
Wood fired thermosiphon cedar hot tub.
Masanobu Fukuoka inspired veg garden & fruit trees
NugentS
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« Reply #7 on: June 14, 2019, 05:44:52 PM »

The only drafts I have found will be dealt with by foaming under ground floor as in there are a couple of holes to under the floor

The mold issue should be dealt with by the open cell nature of the foam which allows breathing. I assume it doesn't therefore insulate as well as closed cell foam - but thats a trade off

I would get the foam professionally done - and from memory of when we had the floor boards up some years ago there is room for a tunnel rat under the floor. a 6'6" 25st individual - maybe not

The boiler does not have an air vent (and I am still alive) - so I guess its the right kind.

 Grin

Sean

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pantsmachine
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« Reply #8 on: June 14, 2019, 09:09:39 PM »

I have no experience in foams beyond the form that comes in 750ml tins(pu), had a blast with those. Just be aware of what you block off and put airflow high on your prioriry list and I'm sure you'll do fine. Huge fan of max insulating to a price/reward return so would agree with previous posts on insulate the hell out of your loft first with old school trapped air types before progressing. Slowly slowly catchy monkey.
« Last Edit: June 14, 2019, 09:11:15 PM by pantsmachine » Logged

HUGE insulation depth.
5.12 kw PV system with Solar edge.
4.8 kw Pylon tech battery storage.
All Low energy bulbs.
Solar I boost charging 210 ltr OSO system tank.
Balanced & zoned CH wet system & Hive 2
Wood fired thermosiphon cedar hot tub.
Masanobu Fukuoka inspired veg garden & fruit trees
kristen
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« Reply #9 on: June 15, 2019, 12:46:22 PM »

Lots of good advice here which I enjoyed reading.

Old part of our houses is very solid (lots of concrete) 1960's.  pressurised air test was under 5 ach without blocking up the chimney and daylight visible around the front door ...

previous owner put a pitched roof on the original concrete flt roof (which incorporated vermiculite or similar insulation), and decent amount of fluffy stuff on top of that They also replaced the Crittall windows with uPVC double glazing.

They were elderly, and could afford oil central heating on 365/24/7 ... they kept snug, that kept moisture at bay

We filled cavity and ran a central heating temperature closer to poor youngster setting. We had condensation on inside of windows in winter, no actual sign of mould growing on walls, but winter coughs / colds which might well be attributed to "spores".

We increased the loft insulation and insulated window reveals (cold bridging etc). We also put in mechanical ventilation (having installed wood burner with external air supply and blocked up the gaps around the front door!) [with heat recovery]. Completely fixed any notion of moulds / damp / condensation on windows in winter.

MVHR is not easy to retro fit - air pipes much bigger diameter than water ones of course.

Beyond that we have built Passive House extension (which provides pretty much all accommodation for wife and I during the Winter). Extension increased floor area by 50%, temperature in old part turned down somewhat, heating fuel reduced by 50%.

Interestingly not had a single winter cough / cold in the 5 years since, even though surrounded by ill people at work all Winter (known benefit of Passive House super-insulation, hermetically sealed + MYHR).

So I echo the comments about watching out for damp problems, that is the likely outcome of improving insulation / air-tightness. But max insulation and zero draughts, along with no cold bridging, would be what I would aim for.
« Last Edit: June 15, 2019, 12:48:34 PM by kristen » Logged
dimengineer
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« Reply #10 on: June 16, 2019, 12:54:15 PM »

I going to surmise here - the MHRV is probably your biggest win.
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dimengineer
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« Reply #11 on: June 16, 2019, 12:59:42 PM »

Dimeng, for your worst room. https://www.condensationproducts.co.uk/product/anti-mould-paint-protection-additive/

We have a number of rental houses and I swear by this stuff.

Thanks. Useful.
We actually dealt with/manage the condensation/mould problem in that room by
a) Thermal wallpaper on the long wall
b) Just spacing the furniture (bookshelves, large) off the wall by a centimetre
c) The last cold spot - bottom corner, by the patio doors - ensure the curtains dont cover the wall just there. Tie backs, basically. (If we forget, in winter, after about 4 weeks, you can just start to see some hints of mould)
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TT
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« Reply #12 on: June 16, 2019, 01:14:25 PM »

the first post advised that downstairs was hard to heat.

I would look at balancing the radiators first to try and improve this.

I have a suspended timber floor and added 100mm rockwool slabs underneath, by going down the hatch, cutting them, and squeezing them in, it made a big difference to the room temperatures in winter
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kristen
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« Reply #13 on: June 16, 2019, 02:18:25 PM »

I going to surmise here - the MHRV is probably your biggest win.

I'd qualify that with air-tightness needing to be very good before embarking on MVHR.

The Heat Recovery needs the incoming / outgoing air, though heat exchanger, to be balanced in order to recover heat as per Spec. MVHR has the building under positive pressure (AFAIK - pushing air in drives it out of rooms with air-exhausts? Probably some pumping too, "pulling" air through the rooms with air exhausts, but I'm guessing the net-sum is positive-pressure)

If there is air leakage from the building then air going out through exhaust will be less than fresh air coming in, and heat transfer will be below-par.

I don't know the maths, but I have read that this effect causes a significant heat loss.
« Last Edit: June 16, 2019, 09:19:38 PM by kristen » Logged
NugentS
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« Reply #14 on: June 16, 2019, 03:15:09 PM »

the first post advised that downstairs was hard to heat.

I would look at balancing the radiators first to try and improve this.

I have a suspended timber floor and added 100mm rockwool slabs underneath, by going down the hatch, cutting them, and squeezing them in, it made a big difference to the room temperatures in winter

Downstairs has a smart radiator system. There is a room thermostat as well as an electronic TRV on each rad. The smart thermostat tells the rads to turn on or off. Both rads turn on and off correctly - but I shall check again come Winter (I usually do).

Sean
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