Damp control on a budget

[brianos]

great thread. quick side question sort of still on topic - can anyone recommend a decent tool to remove plaster (which I think is a cement & sand mix (I'm possibly using the wrong terminology). I do know its military grade tough and would likely survive a direct hit. but give it water and it starts to fall apart. I digress).

I've seen SDS drills advertised but no idea if they're effective or what level kit required to break this render off. any guidance appreciated.

 

[paulc]

I've been using a cheap air hammer & chisel set that I picked up from Lidl a few years back. Light weight, and easy to control. But it needs a bigger compressor than I have (claims to be an 8CFM model).
An SDS drill is likely to work out cheaper even although you can't use one for spraying.

 

[aockenden]

Yes a medium-duty SDS is the way to go for hacking off cement.

 

[brianos]

right. I've just purchased this bad boy......

 

[mh12]

Ca

Ps we are overall in a similar experience, old house and lots of problems. I've kept costs down by enthusiastic DIY and learning lots along the way. Working room by room. Have now got 4 rooms fully insulated with wood fibre, did the plastering myself (started in a cupboard to practice). Taken a lot of time to do but if you're working on a budget you can save a lot by getting handy!

I'm in a very similar position and torn by the various options available. Essentially need to internally insulate a Victorian house with solid walls (IWI system). Can I ask did you remove all existing plaster i.e. bare to brick? What was the method of attached the wood fibre board to the wall- mechanically fixed or with lime plaster? What thickness of fibre board did you opt for? And what thickness of lime plaster finish did you apply on the wood fibre board?
Has anyone come across SWIP system of IWI? Dunno what the difference on price would be between SWIP and fibreboard + lime plaster method of insulation
Sorry, i'm a bit of a novice.

 

[Lacan07]

Ca

I'm in a very similar position and torn by the various options available. Essentially need to internally insulate a Victorian house with solid walls (IWI system). Can I ask did you remove all existing plaster i.e. bare to brick? What was the method of attached the wood fibre board to the wall- mechanically fixed or with lime plaster? What thickness of fibre board did you opt for? And what thickness of lime plaster finish did you apply on the wood fibre board?
Has anyone come across SWIP system of IWI? Dunno what the difference on price would be between SWIP and fibreboard + lime plaster method of insulation
Sorry, i'm a bit of a novice.

No, if you can get down to the original lime plaster (it might be hiding under emulsion paint or wallpaper) then that will save you a hell of a lot of money and effort. You can just apply the wood fibre board on top with insulation nails. They say between 40mm - 80mm is the right thickness for IWI, any thicker will move the dew point dangerously into the fabric of the building. Remember breathable IWI is allowing the warm moist air to escape through the walls, you're not preventing it as you normally would in a warm roof insulation set up. There's loads of 'how to' guides on plastering wood fibre on the internet.

 

[larry]

Hi mh12, so no don't remove the existing plaster.... Only if it's blown and is falling off. You need a parge coat for air tightness, so the existing plaster needs to stay on and you fill any chunks which come off with lime plaster (e.g..NHL mixed with sand). You need to remove as much paint and old paper as you can from the original.

Rigid wood fibre boards are fixed with mechanical fixings i.e. thermally broken anchor pins. I think mine were 180mm long for 100mm rigid wood fibre boards.

Flexi wood fibre boards need to be installed between battens/studs. This is my preferred method as I then have got something to fix wall items to afterwards. I've done this by battening and then counter battening, 40mm each layer, which also means you help reduce cold bridging. However you then need to add a final layer for plastering (as you can't plaster directly onto Flexi boards like you can rigid). I've used 20mm rigid wood fibre board or in some cases plasterboard.
You could (I guess...?) combine both rigid and flexi starting with battens for 40mm Flexi and then directly fix 40mm or 50mm of rigid over the top.

Plenty of options for lime plaster over the top. Doing it DIY I've had success with Breathaplasta but I know others on the forum who will make other recommendations. Use a reinforced fibreglass mesh between the plaster layers. Thickness - follow the instructions...

Don't know anything about SWIP

 

[mh12]

Thank you for the responses.
larry, can you expand a little bit please in terms of the spacing of the batten method what the distance between each batten. Will the flexi wood fibre boards need to be cut to size to fit between parallel battens or should the spacing between the battens be similar to the width of the flexi batts to avoid any wastage of insulation.
Is installing the battens and applying insulation a DIY job or is it best left to the carpenters?plasters?.
In terms of the counter battening method am I correct in assuming if the 1st battens fixed to old lime plaster/bare brick were vertically attached then the counter/2nd set of batten need to be horizontally fixed?
Thanks

 

[a twig]

Lists of useful information in this thread covering both wood wool and wood fibre insulation options and installation methods

 

[mh12]

No, if you can get down to the original lime plaster (it might be hiding under emulsion paint or wallpaper) then that will save you a hell of a lot of money and effort. You can just apply the wood fibre board on top with insulation nails. They say between 40mm - 80mm is the right thickness for IWI, any thicker will move the dew point dangerously into the fabric of the building. Remember breathable IWI is allowing the warm moist air to escape through the walls, you're not preventing it as you normally would in a warm roof insulation set up. There's loads of 'how to' guides on plastering wood fibre on the internet.

Thank you Lacan07.
After extensively reading historic England guidance of IWI in old properties with solid walls it appears interstitial condensation is a risk. You mention thickness of 40-80mm to avoid dew point is this guidance from the like of historic England?
Also if some of the walls are bare brick is the recommendation to apply a thin coat of lime plaster to even the surface for the application fo wood fibre boards?
Finally what provisions will have to made for electrical switches- a rectangular cut through the fibre board?

 

[mh12]

Lists of useful information in this thread covering both wood wool and wood fibre insulation options and installation methods

I've clicked on the thread but it doesnt appear to be leading me to the intended post. Can you please post again
Thankls

 

[a twig]

Fixed

 

[larry]

Thank you for the responses.
larry, can you expand a little bit please in terms of the spacing of the batten method what the distance between each batten. Will the flexi wood fibre boards need to be cut to size to fit between parallel battens or should the spacing between the battens be similar to the width of the flexi batts to avoid any wastage of insulation.
Is installing the battens and applying insulation a DIY job or is it best left to the carpenters?plasters?.
In terms of the counter battening method am I correct in assuming if the 1st battens fixed to old lime plaster/bare brick were vertically attached then the counter/2nd set of batten need to be horizontally fixed?
Thanks

Sure. You just set the spacing to fit the insulation. So, 575mm, I make sure the gap is approx 570mm to give a snug fit.
Yes, counter battening means exactly that.
Whether it's DIY or not depends on your skill, confidence and levels of perfectionism (and possibly your access to tradespeople). I have done it DIY and have low skill but will basically give anything a go....!!

 

[Stevers]

The last professional job on this house was to replace a missing chimney that I felt was well beyond my pay grade as a DIY'er then in full time work with a long commute.

Since then I've done all sorts of fairly serious jobs, reading up on how they should be done, and expecting to spend much longer on them than any tradesmen could afford to take. I have a reasonable set of tools, many being secondhand bargains or hand me downs. I did a bit of woodwork in secondary school that introduced me to the joys of a wedged mortice and tenon joint using hand tools, and have had to grow in the job getting better over time. You do need to evaluate what went well and what didn't, and have a fairly critical eye for what is going to look 'right' and what won't long term. I strive for a period correct look, and now have a house that looks like it's always been loved and well cared for, which sadly wasn't the case.

Overall, DIY needs to be viewed as a hobby that is of financial benefit, is (mostly!) good for mental health, and excellent for hand eye co-ordination. It can, needless to say, be extremely satisfying.

 

[Lacan07]

Thank you Lacan07.
After extensively reading historic England guidance of IWI in old properties with solid walls it appears interstitial condensation is a risk. You mention thickness of 40-80mm to avoid dew point is this guidance from the like of historic England?
Also if some of the walls are bare brick is the recommendation to apply a thin coat of lime plaster to even the surface for the application fo wood fibre boards?
Finally what provisions will have to made for electrical switches- a rectangular cut through the fibre board?

Hi, I can't speak for historic England but when I was researching the subject 3 or 4 years ago when I purchased my house 80mm was considered the cut off point for solid bricks walls. I recently stumbled upon a thread on the Green building forum where a regular contributor who used to work for one of the wood fibre producers (I think it was likely Steico) confirmed that they had thoroughly tested their product with solid brick walls (9") for interstitial condensation and there was no risk up to approx. 80mm.

A brave man might venture to 100mm, personally when I begin work downstairs I'll likely opt for 60mm.

The aim is to have no gaps between the board and the wall, if your brick work is super flat you can apply wood fibre straight on to brick without the need for lime plaster. Its worth noting there is some 'give' in the 40 - 60mm board which could account for undulations, etc. Alternatively some producers provide a type of lime 'fixative' to apply to the back of the boards to account for any subtle gaps but these are mostly likely all NHL based lime products which won't be as breathable as non hydrated lime, so one may prefer to prepare uneven walls with the classic scratch and float coats to ensure maximum efficiency.

There is nothing in the building codes that stipulate you have to protect electrical wires from lime plaster but use of conduit is advisable for peace of mind. When insulation is being used I think electricians employ a particular type of metal back box that sits on the brick, (i.e not chased into the brick). You cut the wood fibre to the shape of the box.

 

[mh12]

Sure. You just set the spacing to fit the insulation. So, 575mm, I make sure the gap is approx 570mm to give a snug fit.
Yes, counter battening means exactly that.
Whether it's DIY or not depends on your skill, confidence and levels of perfectionism (and possibly your access to tradespeople). I have done it DIY and have low skill but will basically give anything a go....!!

Would you consider adding a vapour control check layer between the 1st and 2nd layer of battens to restrict air vapour travelling to the brick wall?
Also what batten size would you consider to make sure the insulation thickness is the same depth as the batten thickness depth in order that you get a flush finish?

 

[a twig]

Most sparkles I’ve seen just stick a bit of batten behind a standard metal back box as a spacer to bring it forward and provide a thermal break between the wall and the back box.

Alternatively I’ve seen plastic surface mount style back boxes used as recessed in this situation as well, but can’t comment on whether that’s a good idea or not

 

[larry]

Would you consider adding a vapour control check layer between the 1st and 2nd layer of battens to restrict air vapour travelling to the brick wall?
Also what batten size would you consider to make sure the insulation thickness is the same depth as the batten thickness depth in order that you get a flush finish?

I didn't add a vapour check layer, in my mind the point of wood fibre isn't to restrict breathability at all and the hygroscopicity is your friend for moisture control (others might have more to say here).

I used 3x2 treated CLS with 40mm insulation with the 3 inch width against the wall. The finished size of the short edge of 3x2 CLS is between 38 and 45mm depending where you buy from and is perfect for 40mm insulation (38mm is more perfect than 45mm as it packs down tight; you could use 50mm thickness insulation with a 45mm batten if you wanted).

For sockets, you can get intumescent pads which expand in case of fire to go at the back of the back box... Given the material (I know it's been treated) I wonder views on whether that a good idea? Or overkill?