Building Extension now & planning EWI in future

little_monty

I'll soon be building an extension to by Bungalow.

The 3 External walls of this extension will be very well insulated, i.e. with insulation within the wall itself and also with internal wall insulation.

Additionally 1 of the external walls will be cladded on the outside.

My intention in coming years is to Externally Insulate all the Bungalow walls.

Assuming the External Wall Insulation grant is still available, Would it be necessary to Externally insulate the new already well insulated Extension ?

The SEAI site talks about the 'optimum solution', but I'm just wondering how the call is made on situations like this.

Rabbo

The SEAI Better Energy Homes grant has a requirement U value for walls of 0.27. If you could demonstrate to them that the extension was newly constructed and exceeds the target u value of 0.27, Id imagine you wouldnt be required to carry out the improvement works to the extension. Additionally, it is common for extensions to be constructed to houses while undetaking insulation works to the original house under the SEAI scheme. Surely your case would viewed to be similar. Best advice is to contact SEAI and ask.

sydthebeat

To be eligible to apply to the Better Energy Homes scheme, your home must be built before 2006. Homes built from 2006 onwards should have been constructed to the 2003 Building Regulations and so should not require significant insulations or heating system upgrades. - See more at: http://www.seai.ie/Grants/Better_energy_homes/Better_Energy_FAQ/#sthash.RSxvSqSO.dpuf

technically you need to build now to 2011 regulations

little_monty

Thanks for the comments guys.

As suggested I contacted SEAI who did confirm I would Not need to externally insulate any new extension to qualify for EWI grant for original bungalow as long as new extension is finished/insulated to 2011 standards

(I'm waiting to hear back from them what 'proof' might be required to show I've met these standards. At the moment I've an architect & builder but I don't see reason to have the job certified by an engineer (extension is relatively straightforward, I've no intention of selling etc)

Outkast_IRE

Why are you insulating in the cavity and internally ?

I was under the impression best practice is to try and keep all the insulation in a single layer. Also wouldn't it be cheaper to keep the insulation in one layer rather than buying two seperate insulations

little_monty

Hi Outcast,

Yes, perhaps.. I'm only at stage of getting indicative quotes yet. I've specified that extension should be well insulated and meet building reg's but haven't looked into or discussed details on how these should be met yet.

Rabbo

You should have a professional specifying the works and not be relying on builders for a proposal.

Outkast_IRE

little_monty wrote: »

Hi Outcast,

Yes, perhaps.. I'm only at stage of getting indicative quotes yet. I've specified that extension should be well insulated and meet building reg's but haven't looked into or discussed details on how these should be met yet.

Personally i would prefer to have the insulation in the cavity only, as i do think having the internal block work generally will create a more comfortable room with greater temperature stability.

But obviously someone would need to look at your exact situation and see is this feasible.

MicktheMan

little_monty wrote: »

The 3 External walls of this extension will be very well insulated, i.e. with insulation within the wall itself and also with internal wall insulation.

Why not use block on flat externally insulated for the new extension? This will then blend well with the original house when it is externally insulated later.

Also, don't forget about your air tightness.

Calahonda52

EWI all the way around, otherwise its a dog's dinner, How far onto the xtension will the EWI come to reduce " thermal bridging", may not be the 100% terminology....
With the xtension u have chance to do EWI correctly right from foundations up into roof space

Outkast_IRE

If you are planning EWI in the future the only sensible thing is to do the extension in it now. You will be able to design for the EWI finish now rather than needing to mess with window sills etc if you leave it until the future.

little_monty

Thanks for all the comments.

I take the point the combination of EWi on existing house with something else in the extension is not ideal.

My worry with externally insulating extension now is I suspect it might cost a lot more plus complications of dealing with multiple contractors plus worry the EWI might not be done right.

Anyway I will consider this further with architect builders and perhaps an EWI company

If anyone can suggest \ pm a decent EWI company covering Kildare that would be great

murschauds

• You can design your extension to take account of doing EWI on the main structure at a later date. If for example you are going to apply 100mm insulation in the future, you could pull the footprint of your extension out by about 108/110mm which will accommodate the application of the EWI on the original building in the future. But you need to talk to your Architect.
• You will have a potential cold bridge between the new and old structure if you do as you are proposing, but this could be minimised by utilising thermal laminate boards on the internal in conjunction with the cavity insulation (and the increased floor space from the above measure, means you won't be losing any internal space), and bring the laminate boards into the original structure (from the new) by at least 600mm.
• If you can do the complete EWI job (on the new build and the original structure), it would be better to do it all together. If you can't, the two applications can be married together, however you will have a joint between the two but this can be incorporated into an expansion joint. Or else hidden behind a displaced downpipe or whatever.
• If you are going to do cavity and/or internal insulation on the new build, it is really important that you use the same render to finish the external of the new build as you will to do with the EWI job in the future. So pick what EWI system you will go with now. Different renders available are Mineral, Acrylic, Silicone, Silicate and Nanotechnology (and of course dry & wet dash). They each have pros & cons. Pick one that suits your build (new & especially old), and don't let the contractor/builder decide for you.
• I can give you a number of good Contractors covering the Kildare region that I can vouch for. PM me if you wish me to provide you with them.

little_monty

Just to give an update here as I finally get close to kicking off the work

I am going to Externally insulate both the existing house and the new extension.

The existing house has 100mm cavity with 50mm of rigid insulation (appears to be tight against outer leaf).
So i'll have these walls pumped up the full height of the wall (so sofit will have to be removed)

I'm going with 100mm EPS external insulation.

The EWI company has recommended I build extension with similar cavity wall as existing house (all this cavity will be pumped)
though I have fully ruled out option of building solid walls with block on flat yet