external insulation and rendering

[jenjenoz]

Hi,
Just joined this forum and really hoping to get some advice.
We have bought a property in Bulgaria which is a single walled hollow brick type construction, we really need advice on what to insulate the outside with and what you put over the insuation to render onto, also any mixes/additives anyone can recommend.
Thanks, Ken.

 

[noseall]

the building in this topic has been insulated and rendered.

there is a link to a metal lathe site a few posts down.

 

[jenjenoz]

Thanks,
Had a look but that really hasn't helped me.1st do i put a coat on to seal the blocks?.What type of insulation do i use,was told polystyrene boards werent any good, as it doesn't deter vermin etc.The stuff that is used to hold the rendering is it built on a frame work?.As to the rendering,whats the mix and is it painted with something other than masonry paint.Theres also the problem that the temperatures vary from -20 /30 to +100.Also before somebody suggests getting professional builders in,in Bulgaria like finding a needle in a hay stack,whatever job i do with this will be better than their (maestros)experts.Also the sand out there is a problem,its like a river sand,they don't do building sand,just riddle the coarse sand.
Ken

 

[corrie]

You don`t have that many options unless you buy a "system" from a manufacture. You would also need a plasterer to get good results. You have returns arrises ingoes all to consider.

Polystyrene like Kingspan wont be exposed to vermin if it`s behind the lathe and render? Maybe it`s cockroaches or something .

A basic insulation system would be 30 mm Kingspan or similar and Expamet Riblath. Offer insulation to wall with lath over the top and drill plug hole through lathe and board. The holes are drilled through the metal rib of the lath. If you use lathe without the rib you will need a fixing with a flat top head to catch the wire lathe.You can use building paper between lath and wire if you want to avoid adhesion ie breaking bond.

Three coats of render on top of lathe . First coat 6mm pricking coat 3 sand 1 cement SCRATCH IT. Second coat 10mm 4 sand 1 cement. SCRATCH. Final smooth floating coat 8mm 4sand 1 cement. Straighten this coat and sponge it . You can masonary paint it 4wks later.

Now this is a purely rough guide there are scores of specialist systems that I don`t think you will be ably to buy or get applied where you are.

I have used that method and it does work. I have only mentioned the 30 mm insulation as it would give you the least bother to fit. It may not give the u value of 75 mm but that would give you probs in a DIY installation.

Alex

 

[jenjenoz]

Thanks Alex,
This is really good advice.Couple of questions.1, the quality of sand is not very good ,would i be better adding additives to the mix, and if so which?.
2, Is there only metal covering or can you use a plastic one?,and do you run a edging around the house at the bottom to sit the lathe onto.
Thank you.
Ken.

 

[corrie]

You mentioned the Sand. It should be well washed and should be on the slightly coarser grade of building sand...but not as sharp as concrete. It is actually called plaster sand. As long as it is washed it will be ok...no coal or staining minerals.......well maybe GOLD

An ordinary waterproofing/plasticiser is all you need . Cementone Freeflow is one.......follow manufacturers instructions don`t put too much in.

I would stop the insulation 300mm from ground level. If you fix a treated timber batten same thickness as insulation you can butt insulation level with it. This will let you put a bellcast stop bead on top of batten and hang slightly lower than batten to form a drip check. Your insulation will be covered now.

You can get plastic mesh but they are for polymer based systems and are different as well as expensive.

 

[jenjenoz]

Thanks.
Is there any sites to try and look at the polymer base systems as well.Would like to cover all the options,and thank you for all the advice.

 

[corrie]

Just do a google on Polymer Render Insulation systems.........loads of links.

Alex

 

[jenjenoz]

thanks