I have some insulation to push into some awkward spaces, including through a narrow (~1") aperture. Insulation (even PIR) is not known for its rigidity under compression. I'm probably looking at multifoil or thin PIR, with stuffing in fibreglass as a backup plan.
Are there tools that would be useful for this? It really wants things that can not only push (or pull the far end or a loose thing), but also disengage when the insulation is in position.
So far I've come up with:
Cable rods, eg:
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I'm not sure whether these are going to bend if they meet any obstacles?
Drain rods
- similarly, only perhaps more robust?
Fire irons
- good in compression, strong and long, but usually rather chunky (cast iron etc)
Cable rods are awesome! But not that good at pushing stuff - far too flimsy. They are just about strong enough to push themselves - but really come into their own when pulling something else after they have been pushed into place.
Yup - significantly stiffer - and may times the diameter.
PIR board can be tapped into place with a load spreading timber and a hammer. Other types are not easy to force into tight spaces unless you can open them up for the purpose IME.
PIR, even an inch thick is very rigid though. You would have to impose quite considerable force to damage it when pushing a section along its long edge. Whether you can install it snugly clamped to the warm side through this aperature is another matter.
There is always expanding foam.
A photo would help. Is this a bus, van or canal boat ?.
It's a house. There are some bits of plasterboard-faced rafter that I can get access to the bottom end of, but not the flat surface (without much disturbance of ceiling). Think roughly a pillar box with a 120mm tall slot. One of them has a (structural? very solidly nailed anyway) noggin across it such that there's only about a 20-25mm gap. The bottom surface is the back of the ceiling plasterboard and the top surface tar-based sarking (+sarking boards). The depth of the recess to fill is about 1-1.5m.
I can ram in fibreglass to the 120mm gap, but I'd like to put something with foil. PIR would be fine (it's rigid enough) but to get an interference fit requires a lot of force and it would probably buckle. I could fit it loose and then foam, but that would be impossible to remove if it went wrong or needed access in future. I could just fit bare foil (probably that foiled bubble wrap stuff) and ram in fibreglass on top I suppose.
For the noggin one the options are very limited. I was thinking of 'posting' multifoil through the gap and leaving it to sit there. Hence wanted something to manipulate through the tiny gap.
My cousins hubby packed rockwool into the 'eaves' of their link detached house, where there was a valley on top of the party wall connecting to next property. The other side of the roof has a proper overhanging soffit with vents, but the valley side had no ventilation and was where the bathroom was. Over the years moisture vapour from the bathroom (electric shower) permeated the loft above and saturated this rockwool in contact with the wall plate and the ends of the roof trusses and caused significant wet rot issues. So be careful where you 'stuff' insulation without carefully considering ventilation, especially this situation where there is very restricted access.
Got to agree with Andrew never push insulation right up to the eaves and up to the sarking this will block vital ventilation. If needs be stagger the insulation if for instance putting in 270mm of rock wool put a 100mm layer as far as it will go and still leave a gap between rafters then add the 170mm layer finishing shorter than the first layer so you can still see a clear gap. You can get eaves ventilators that fit between rafters and maintain the ventilation gap but these are best fitted when constructing the roof.
I've used the fibre glass bendy-elastic-connected tent poles from my dome tent several times to route things - they look similar. For a fraction of the price plus a free tent :-)
Hmm, that's a thought. (or any other kind of non-pushable stuff between pushable layers, like multifoil between rigid plastic sheets.)
I've been doing a bit of experimentation. It turns out that a drain rod with a rubber disc on the end was an acceptable tool for pulling out wads of fibreglass. I might investigate getting other drain rod fittings to make this a bit easier - perhaps the corkscrew kind.
And 50mm celotex has enough rigidity that I can push in 1.2m lengths without it wobbling around. I've done a few and it's a decent interference fit - will need a hammer to tap them into final position but otherwise good.
For the tricky bit, here's a picture:
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torch beam shows where I want to get the insulation in. However now I look at it, I realise this is the side of the dormer (edge just about visible through the hatch on the left). There is obviously this gap, but I need to do some more (thermal) pictures to work out whether it's all accessible or whether there's more noggins further up that would block insertion.
On the moisture front, I did find a patch of damp insulation, which is directly above the light switch for the toilet. It may be that warm air is leaking through the holes for the wiring and condensing on the fibreglass. I'll have to try and seal the hole. Celotexing this bay may be tricky due to the screw protrusions. Are there any plasterboard fixings that don't protrude much into the cavity? Something a bit like a rivet that surrounds the hole, perhaps?
There is an easy solution. Simply saw through and remove that noggin. It is not structural and can be replaced an inch or so towards the sarking felt without impeding airflow. Once it is removed/replaced you have more room to get PIR and rockwool into place without touching the sarking felt.
You can always replace the noggin with the same dimensions but fitted long side horizontally if needed, or you can simply fit a galvanised strap bar under the rafters joining them together. This will allow plasterboard to be overlaid easily. You can remove a small amount of wood from the underside of thos rafters to allow the strap to sit flush with the underside of the rafter if you want.
There is a dark mark below the torch beam, to the right of the door? frame. Has water leaked in there somehow ?.
Yup... although its got a couple of 4" nails in each end by the looks of it - so saw it in the middle and then hammer it out of the way so that the halves pull off the nails (which can then be tapped out once you have access to the pointy end.
I now realise: since I have access to the back side, I can bolt through from the cavity side. The bolt heads won't protrude as much as a screw or cavity fixing would. If I glue them in place they shouldn't fall out when I screw things onto them.
It seems to be supported by the door frame which is providing more support than the noggin, provided the top rail of the frame is well fixed.
One end of a horizontal noggin provides almost resistance to a downwards acting force (of the roof). The fact that it has not deflected seems to suggest that it is only providing lateral resistance to warping of the rafters.
I can't really tell what is going on from that photo. However if you are concerned that its there for a particular reason - then fix another
*under* the rafters before you take out the existing one. That way it remains restrained/supported etc, but you also open up a straight line of sight into the space.
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