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james1
31st October 2007, 05:18 PM
Folks,

I'm renovating a mass concrete house built circa 1936. walls are 14inches thick comprising of a lightweight aggregare concrete. The walls are in good enough nick except for the chimney's which are built into the gable ends. There's some penetrating damp from some thermal cracks in the chimney and around some window reveals. The site is exposed to southly atlantic rain (quite often!)

What i need to decide on is what the best option is to prevent the penetrating damp.

I've looked at the external insulation systems and new acrylic renders as well as possibly using an olryd plastering membrane. The costs of all these are quite high and i'm not sure if i'll get a benefit over and above sand/cement/ wet dash.

One idea i've had is whether i could use something like the Paroc or expanded polystyrene as insulation with traditional sand/cement scratch coat and wet dash on top?. This would even out the costs a bit but i'm not sure if there's enough suction to keep the render on. I presume there would be.

I know it's not the norm but sure might be worth a try? has anyone any thoughts sugestions.

thanks

leonard

VikingHouse
1st November 2007, 04:47 PM
Hi Leonard

Better to use the Fiber glass mesh supported breathable silicone plaster that is designed for these applications.
You also get better water-proofing with these specialised plasters.

passivehomes
1st November 2007, 08:46 PM
hi Leonhard,
If you use any aditional insulation to your building, you can only use special adhesive with fiber mesh and acrylic finish. www.sakret.de .( Product; KAM SAN and SILIKAT finish). or STO or Weber or Maxit has the right product.
passivhomes

james1
2nd November 2007, 04:18 PM
thanks guys,

It's a pity these products are so expensive!


leonard

VikingHouse
2nd November 2007, 09:58 PM
Try Sanderwood Stone in Offaly. Best prices in the country!

sinnerboy
4th November 2007, 01:51 PM
Why not re render externally , conventionally and use composite plasterboard/insulation internally .

VikingHouse
19th November 2007, 08:17 PM
Why not re render externally , conventionally and use composite plasterboard/insulation internally .

Hi Sinnerboy

In older buildings the joists and internal walls are physically keyed into the outer walls, so it is not possible to insert a membrane or insulation behind them.
The internal plasterboard/insulation not only makes the cold bridging of these elements worse, but also reduces the amount of hygroscopic buffering and vapour transmission in the room.
Both these factors thus increase the chance of condensation, mould and, in the case of the floor/ceiling joist, structural failure, where the dry lining is unable to reach.
There are some very good examples of this in recently renovated/drylined Victorian Hospitals in England, which now have serious outbreaks of dry rot in joist ends, where none existed 5 years ago.

sinnerboy
20th November 2007, 01:16 PM
Hi Sinnerboy

In older buildings the joists and internal walls are physically keyed into the outer walls, so it is not possible to insert a membrane or insulation behind them.
The internal plasterboard/insulation not only makes the cold bridging of these elements worse, but also reduces the amount of hygroscopic buffering and vapour transmission in the room.
Both these factors thus increase the chance of condensation, mould and, in the case of the floor/ceiling joist, structural failure, where the dry lining is unable to reach.
There are some very good examples of this in recently renovated/drylined Victorian Hospitals in England, which now have serious outbreaks of dry rot in joist ends, where none existed 5 years ago.

Hi Viking House

What do you make of the detail at page 5 here - timber intermediate floor

http://www.planningportal.gov.uk/uploads/br/masonry_internal_wall_insulation_illustrations.pdf

one particaular item I would draw to your attention - in middle third section

- wall joints around joists are to be pointed with sealant

This appears to directly confilct with the ( reasonable ) points you have raised

Can you post any links relating to the failures in those UK hospitals ?

VikingHouse
20th November 2007, 07:27 PM
Wall joints around joists are to be painted with sealant
This appears to directly confilct with the ( reasonable ) points you have raised

Painting a joist at the external wall junction protects it from moisture in the block and from outside.
The problem I am highlighting is from internal water vapour getting into the joist and travelling hydroscopically to where it meets the cold wall where it condenses.
In order to protect the joist properly when drylining you would have to remove all the floorboards and paint the whole joist completly.
There is also the problem of too many Cold Bridges and Condensation/Mould forming on the Cold wall behind the Drylining.
England is the world leader when it comes to the incidence of Asthma and they for sure don't have the dampest climate, just damp houses and we are copying them.

Why not copy the Scandinavians or the Germans who seem to be doing a much better job?

Here is a 34 page document on the subject Brian. It takes a bit of digesting, better to print it off.
http://www.natural-building.co.uk/pdfs/Breathability_in_buildings.pdf

dgray_ie
10th January 2009, 03:12 PM
Hi,

Can anyone tell me who I would contact to get a quote for Sto acrylic render.

I was looking at the option of building a timber frame house using 302 I beam walls clad with panelvent on the outside followed with Pro-Clima Solitex WA, cavity for drainage/vent space made from 50x25mm battens, followed by Sto Acrylic render approx 30mm thick. I was looking to see if it has an Irish or British Agrement Cert but I couldn't see anything.

Can anyone tell me who I would contact to get a quote for Sto acrylic render. Is there an agent? Can anyone recommend reputable installers of this system?

Thanks

mahoney.john
30th June 2009, 04:02 PM
Folks,

I'm renovating a mass concrete house built circa 1936. walls are 14inches thick comprising of a lightweight aggregare concrete. The wall insulation (http://www.techstore.ie/Renewable-Energy/Wall-Insulation.html) are in good enough nick except for the chimney's which are built into the gable ends. There's some penetrating damp from some thermal cracks in the chimney and around some window reveals. The site is exposed to southly atlantic rain (quite often!)

What i need to decide on is what the best option is to prevent the penetrating damp.

I've looked at the external insulation systems and new acrylic renders as well as possibly using an olryd plastering membrane. The costs of all these are quite high and i'm not sure if i'll get a benefit over and above sand/cement/ wet dash.

One idea i've had is whether i could use something like the Paroc or expanded polystyrene as insulation with traditional sand/cement scratch coat and wet dash on top?. This would even out the costs a bit but i'm not sure if there's enough suction to keep the render on. I presume there would be.

I know it's not the norm but sure might be worth a try? has anyone any thoughts sugestions.

thanks

leonard

There are many types of Insulation material used in building walls, such as;

* Rock Wool, Mineral Wool and Slag Wool
* Fibre Glass Insulation
* Cellulosic material (Cotton and Recycled Paper)
* Expanded Polystyrene foam & Outsulation (Rigidfoam or EPS foam)
* Poly Urethane Foam (PU)
* Poly Ethylene Foam (PE)
* Butyl/ Nitrile Rubber closed cell insulation
The last 4 named are synthetic material and are based on petroleum byproducts.

Where to use what?

Virtually any conventional insulation material can be used as wall insulation subject to the location and the properties desired.

If retrofitting (under the warmer homes scheme for eg.) is desired the cavity wall in filling is the only
option available at low cost.

Here too only the continuous cavity holes can be injected with insulation.Desirable Properties of Wall insulation
Primarily the wall insulation is expected to act as a barrier for the ingress of undesirable heat.

Chopper
30th June 2009, 04:36 PM
Hi,

Can anyone tell me who I would contact to get a quote for Sto acrylic render.




Try www.smce.ie they've done three houses for me and so far so good.

chavis
13th July 2009, 08:02 AM
Folks,

What i need to decide on is what the best option is to prevent the penetrating damp.

One idea i've had is whether i could use something like the Paroc or expanded polystyrene as wall insulation (http://www.techstore.ie/Renewable-Energy/Wall-Insulation.html) with traditional sand/cement scratch coat and wet dash on top?. This would even out the costs a bit but i'm not sure if there's enough suction to keep the render on. I presume there would be.

I know it's not the norm but sure might be worth a try? has anyone any thoughts sugestions.

thanks

leonard

hi,
Virtually any conventional insulation material can be used as wall insulation subject to the location and the properties desired.

If retrofitting (under the warmer homes scheme for eg.) is desired the cavity wall in filling is the only
option available at low cost.

Here too only the continuous cavity holes can be injected with insulation.Desirable Properties of Wall insulation
Primarily the wall insulation is expected to act as a barrier for the ingress of undesirable heat.
thanks

chavis
18th July 2009, 06:41 AM
Folks,

I'm renovating a mass concrete house built circa 1936. walls are 14inches thick comprising of a lightweight aggregare concrete. The walls are in good enough nick except for the chimney's which are built into the gable ends. There's some penetrating damp from some thermal cracks in the chimney and around some window reveals. The site is exposed to southly atlantic rain (quite often!)

What i need to decide on is what the best option is to prevent the penetrating damp.

I've looked at the external insulation systems and new acrylic renders as well as possibly using an olryd plastering membrane. The costs of all these are quite high and i'm not sure if i'll get a benefit over and above sand/cement/ wet dash.

One idea i've had is whether i could use something like the Paroc or expanded polystyrene as wall insulation (http://www.techstore.ie/Renewable-Energy/Wall-Insulation.html) with traditional sand/cement scratch coat and wet dash on top?. This would even out the costs a bit but i'm not sure if there's enough suction to keep the render on. I presume there would be.

I know it's not the norm but sure might be worth a try? has anyone any thoughts sugestions.

thanks

leonard

Virtually any conventional insulation material can be used as wall insulation subject to the location and the properties desired.

If retrofitting (under the warmer homes scheme for eg.) is desired the cavity wall in filling is the only
option available at low cost.

Here too only the continuous cavity holes can be injected with insulation.Desirable Properties of Wall insulation
Primarily the wall insulation is expected to act as a barrier for the ingress of undesirable heat.