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08-07-2010, 19:28   #1
ECO_Mental
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External Cladding_ Concrete Block vs Cement Board

Hi all,

I am about 95% sure I will be going with a timber frame house but the one last issue I have is what external cladding will I use. I would love to put on cement board cladding with render as I feel this is a lot neater solution than block work. It might also work better with my house design, but the only problem is cost (isn’t it always...)

Anyway has anybody of you out there worked out the finished price for cement board and concrete block finish? Including painting plastering etc, etc.

I have gotten an estimate off one timber frame manufacturer of €73m2 for cement board and €23m2 for block work. Are these numbers ok or can it be done cheaper?


Tipping away like a little dumper
EM
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13-07-2010, 23:30   #2
Peter Sweeney
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Cement board finish is fine if installed to NSAI installation standards, however there is little room from error.

If movement joints and staggering of cement boards are not fitted to exacting standards numerous hairline cracks will certainly appear over time as the timber structure drys out.
Even if the boards are fitted to standards, movement in the timber structure can result in cracking at corners and above and below window / door openings beyond the control of the cement board fitter.

These cracks in the cement boards would not normally be structural but can look unsightly especially if your selling your property.

If using cement boards insure that the cement boards are certified to be used in Ireland and also treble check the references of the installer.
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19-07-2010, 13:07   #3
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Quote:
Originally Posted by Peter Sweeney View Post
Cement board finish is fine if installed to NSAI installation standards, however there is little room from error.

If movement joints and staggering of cement boards are not fitted to exacting standards numerous hairline cracks will certainly appear over time as the timber structure drys out.
Even if the boards are fitted to standards, movement in the timber structure can result in cracking at corners and above and below window / door openings beyond the control of the cement board fitter.

These cracks in the cement boards would not normally be structural but can look unsightly especially if your selling your property.

If using cement boards insure that the cement boards are certified to be used in Ireland and also treble check the references of the installer.
I know of 3 buildings done in cement board in recent times: €73 was the lowest price that could be got, and is effectively doing it at cost price. We had it done on two facades here, same. I got a price of €28.5 per sq m for block wall as cladding c/w nap plaster finish, so you're prices are about right.

Now, I know of an extension to a house being built, and it's being done in a non-NSAI board, and the cost is €45 per sq m or thereabouts - as NSAI actually don't do any physical testing you can debate for yourself whether you think the badge is worth the extra €€. The board in question does have certification from another jurisdiction. (no connection, btw, but it's a subject that comes up a lot here).

As for Peter's comment about cement-board on moving on expanding/contracting TF, whilst technically possible, I thing it's more likely it's the quality of the timber used as battening, and the fixing method of it (nails, when you should use screws) that's the issue - not the TF. If movement in TF is of concern, OP could consider one of the other timber based, but non TF systems.
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19-07-2010, 19:41   #4
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Guys

What are the problems in not using NSAI approved boards??? Insurance, signing off build?? or is it just a badge.

I mean if there are boards out there that are being used on the continent like Germany and they are approved there whats the problem? Obviously they are fit for purpose.

EM
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19-07-2010, 20:06   #5
Peter Sweeney
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There might be no problems with a board and renderings that bear a CE marking, but for piece of mind if a product has an NSAI certificiate you have a good idea it will stand up to Irish conditions.

If the board has an European certificate, you should be able to get a copy the certificate and compare what testing the board has undergone compared to the testing carried out by / on behalf of NSAI.

For a building to be signed off as complying with building regulations the materials used should comply with Part D1 of the building regulations.
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20-07-2010, 09:21   #6
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Originally Posted by ECO_Mental View Post
Guys

What are the problems in not using NSAI approved boards??? Insurance, signing off build?? or is it just a badge.

I mean if there are boards out there that are being used on the continent like Germany and they are approved there whats the problem? Obviously they are fit for purpose.

EM
You're right: if the product carries CE certification for similar use already, there is no issue, as the CE certification crosses national boundaries.

Quote:
Originally Posted by Peter Sweeney View Post
There might be no problems with a board and renderings that bear a CE marking, but for piece of mind if a product has an NSAI certificiate you have a good idea it will stand up to Irish conditions.

If the board has an European certificate, you should be able to get a copy the certificate and compare what testing the board has undergone compared to the testing carried out by / on behalf of NSAI.

For a building to be signed off as complying with building regulations the materials used should comply with Part D1 of the building regulations.
NSAI adds cost, and they have no testing facitilies for products like this. And, NSAI certification costs a great deal of money, so the first thing your newly-imported product has to do is..........go up in price, in this market, to get that money back. Then everyone will wonder why the product is XX% cheaper abroad than here/they can buy in the internet/etc etc, and so on and so on............even though the product is identical. And NSAI cert is not a warranty, so there's no comeback to NSAI afaik on it, either.

You do not need NSAI to satisfy Part D1. In fact, you don't any cert, from anywhere at all. Part D1 also accepts 'Performance in Use' as a (comparable) satisfactory measure of the suitability of the product.
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29-07-2010, 21:15   #7
tfer
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I am in the same boat as the op, have been looking at softboard, woodfibre board, 100mm thick and render over. Would do the installation myself but not the render, anyone done this, how did it work out ? am not a big fan of concrete board , any other external options ?
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04-09-2010, 09:43   #8
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Hi - I am also at the stage where all is set with a Timber Frame solution to 100m2 extension. Costings for TF finally reasonable (including Cement Board to exterior), and prices for rest of fit out are getting there. Problem is contractors plasterer hasnt worked to Cement Board before, and research I do online of the various meshes, joint filler, primer coat, base coats, and finish coats suggest this will be very expensive. Am I best to completely forget about this method and get the outside leaf in blockwork (which Id prefer not to!) .

Any comments welcome.
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04-09-2010, 10:13   #9
Peter Sweeney
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If you are going to get a plasterer to finish your house with cement board, make sure he has plenty of experience and practice with cement board and its overall systems.
Don't make the mistake of letting your plaster learn this particular "trade" on your house.
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11-09-2010, 11:22   #10
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The main problem with blockwork is the people building them, at least 80% of them are brutal and unreliable. I know this because because im a blocklayer and had up to 30 working for me during the good times. Depending on where you live i could put you in touch with a good reliable blocklayer. The advantages are better u-value, better sound protection (important for a timber frame), stronger, less prone to cracks, cheaper, less chance of moisture penetration because the blocks are not fixed directly to timber battons.
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13-09-2010, 13:36   #11
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Originally Posted by masonry solutions View Post
The main problem with blockwork is the people building them, at least 80% of them are brutal and unreliable. I know this because because im a blocklayer and had up to 30 working for me during the good times. Depending on where you live i could put you in touch with a good reliable blocklayer. The advantages are better u-value, better sound protection (important for a timber frame), stronger, less prone to cracks, cheaper, less chance of moisture penetration because the blocks are not fixed directly to timber battons.
Better u-value ? Not outside a ventilated cavity it's not. Makes no difference.

You're right about the quality, though. I hear people saying they can get blockwork done now for 40c/block. For 40c, you really are going to get 40c worth.........and it's not what you think.
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26-10-2010, 15:27   #12
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What would happen if you were to use a standard render directly on cement board with no mesh. Basically mesh the joints and skim the board with a thin layer. I have seen this done in the US.... it seemed to ba a sand cement render. I am considering an external insulation DIY job but the rendering has always stopped me until I found a company in Ireland who sell an insulation backed cement board.
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27-10-2010, 12:39   #13
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Originally Posted by Fingallion View Post
What would happen if you were to use a standard render directly on cement board with no mesh. Basically mesh the joints and skim the board with a thin layer. I have seen this done in the US.... it seemed to ba a sand cement render. I am considering an external insulation DIY job but the rendering has always stopped me until I found a company in Ireland who sell an insulation backed cement board.
Well, std sand/cement won't work on most of them. There is a board called 'Durock' which I had used on my own house, and it worked on that - but it was small area (spandrel panel), so not sure how it would be on a big facade.

As for a bonded cement board/insulation - yep, you can get it. It's spec'd for use on flat-roof construction, so cutting down/minimising the ballast you would put on top. It uses the same grade of insulation as we use in our walls - 300kpa XPS - it's called DOW Roofmate LG-X. Problem is, though, price: 120mm thick, w/10mm cement board bonded on: € 49/m2 approx, and a long lead time. I can see the beauty of it, though.

Last edited by galwaytt; 27-10-2010 at 12:47.
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27-10-2010, 12:47   #14
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fwiw - pic here of Acrylic-rendered cementitious board (gable wall)

www.sip-energy.com/SE341/SE341render2.jpg
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27-10-2010, 13:53   #15
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I have a form of synthetic board on my house, Its called blu-clad.
Then on top of that is the synthetic render, made by a German company but also available here.
The process of plastering the wall is quite simple, the base coat goes on and then a fibreglass mesh is trowelled into the wet base coat. Extra reinforcement is used at window corners and doors. The corners are plastic with fibreglass wings that wrap back and secure the corner bead to the wall.
Once dry the top render is applied, I used a nap finish and it only has to be the thickness of the grain in the render.
It has held up well to the conditions here no sign of any algal growth.
Avoid using expanded metal I have seen this give very poor results and eventual failure of the finish.
Mine looks very similar to the pic that GalwayTT posted even the guttering is the same but black!
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