My house was built in 1988. The cavity walls are filled with slabs of rockwool stuff - possibly not as well as I would have liked.
Occassionally I get salesmen trying to sell me the sort of injected cavity wall insulation. They usually claim there is a grant toward it.
I don't like to be pressured - I like to decide if it is a good thing.
Any views?
Your cavity walls ARE insulated. Tell the salesman to EFF OFF.
At that vintage, chances are they are full fill with solid insulation batts. So there will be no space for additional injected insulation.
The trouble with cavity wall bats is that their effectiveness is entirely dependent on how carefully they were fitted when the house was constructed.
The only way you can tell if there are gaps is by use of an infrared camera. (You have to wait for cold weather, turn the house heating up, go outside and search for hot spots after a bout 12 hours). Or you can search for cold spots from inside. Some tool hire places have IR cameras. It's very enlightening,
The camera can detect "hot" footprints when you walk across a carpet!!!
At one time you could get IR film for ordinary cameras but we've now gone digital.
You can drill a hole in the wall in an inconspicuous place to see what insulation you have. Or you might be able to see in the loft with a torch and a mirror.
There is/was a grant for insulation at one time. Dunno what the current position is.
How would they get the existing stuff out? That might be an interesting answer, involving taking the house apart perhaps. I have no cavity walls, but still get leaflets through the door about it and wonder at the waste of rain forest and printers costs at delivering them to houses they cannot fit it to. maybe they will built me a new house? grin. Brian
We had a phone call the other day about insulation- I think loft insulation in this case, my wife answered the phone but the caller hung up when she suggested he spoke to me. He claimed there were grants available etc.
I was suspicious- firstly the call was to her mobile, why hang up, and grants tend to be limited to certain groups ( none of which we fit into).
Being curious, I did a search. Sure enough, grants are available for loft insulation but only in limited circumstances ( which certainly don?t apply to us).
It seems there are companies offering to install insulation, claiming grants are available and to try and secure one for you by completing forms etc. However, they don?t mention to be eligible you need to meet certain criteria AND there seems to be a finite allocation (presumably each year) which is allocated on a first come first serve basis.
They don?t. If the slab stuff has gaps, they can ( in theory) inject the foam stuff to fill them. I?ve heard of it once, how effective it was/is I don?t know.
Is there such a thing as an infrared filter for a digital camera? If so, the LCD should show the image same as a dedicated camera does.
Wrong waveband.
Near infrared is just off the end of the visible spectrum at 750-1000nm. You can get IR pass filters but they mainly make trees look white.
Thermal infrared characteristic of objects at ambient temperatures on Earth is in the 10um band with an order of magnitude longer wavelength. You need special detectors and typically germanium lenses to make images in thermal band IR. You can buy add-ons for mobile phones to do a crude thermal IR camera for not that much (or hire real gear for a price):
How would they establish if the existing cavity wall insulation has gaps?
Different IR band to the cameras designed to detect heat loss, and you can still make a digital camera into an IR camera. The IR band used to detect heat loss, say, from a house is blocked by glass so the glass lenses used in a conventional camera would stop their use for this application in either a (modified) digital camera or a film camera.
The sensors in digital cameras/phones can see IR up to around 1.1um although most may have a filter to exclude some or all of the near IR band. Point your phone camera at the output of your TV remote and press any button and maybe you will see the IR LED flashing. Iphones may have a IR filter on the back camera but possibly not on the front camera.
Military IR cameras and those commonly becoming available for industrial or consumer applications operate in the 3um to 5um band or the 8 to
12/14um band. Cameras fitted to the police helicopters are probably the latter. These cameras most probably have Germanium lenses. To keep costs low (to perhaps a couple of hundred quid) consumer IR cameras may be limited to 64x64 or 100x100 true pixel sensors and have small "slow" wide angle lenses and low video frame rates.A £400 IR camera attachment with a 160 x 120 pixel sensor.
If you have an old digital camera and you want to experiment with near IR (the effect you could obtain with IR film)
If you have any processed colour film negatives around the bits at the end that are completely black can be used as the filter instead of of the Congo Blue filters mentioned in the above article. You could use two bits(double thickness) of this black negative as a stronger filter.
And probably from a company that you wouldn't want to employ if you had to pay for it! These cold caller types appear to be in the same league as those with some left over tarmac for your driveway.
I have some IR pix of my house. Taken from the inside on a cold day so you can see the cold spots.. They are astonishing. I have 600mm insulation my house but there were air leaks. (and cold water pipes)
Full-fill cavity wall insulation needs a modicum of care on the part of the brickies, to avoid creating a cement bridge across the top of a batt before the next rows of blocks + bricks are built and also (more importantly) to avoid dropping mortar onto the top of the installed batt before the next row of batts is pushed down into the cavity.
A 4 inch cavity, with rockwool full fill batts should have the same U vaalue as a 4 inch cavity with 2 inch celotex clamped to the inner leaf, leaving a 2 inch ventilated cavity, but the celotex must be tightly fitted, and clamped to the inner leaf using purpose-made plastic 'wheels' that clip over the wall ties. Ideally, the joints should be taped with aluminium tape too.
I've seen some awful new builds near me, built after 2009 where slabs of inch thick expanded poly were just chucked insde the cavity allowed air flow each side of the insulation , rendering it useless.
Those batts are treated with something to make them water repellent. STill a valid construction method I believe for properties not in those parts subjected to heavy driving rain.
Just tell them your house is a 1930's art-deco house with a flat roof.
You may do more harm than good by adding foam insulation to rockwool slab insulation as there is a danger of bridging the cavity which could cause damp problems.
In any event you would are unlikely to significantly improve the u-value enough to justify the cost of filling with foam.
yes, you can remove it to ge a little IR sensitivity.
hardly. IR near to red (ie red hot emitted IR) & room temperature emitted IR are not the same frequency range.
NT
I suspect they didn?t ;-)
They drill a number of holes on the mortar lines and put a camera in.
SteveW
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.