Dry November: Stay snug with our advice on dry-lining your walls
You Take This Into If Picture: Have Frame Kya Timber Older Your To Might Existing Effective More You Remove Want Kingspan And Home, Frame, K17 Reinstate Plasterboard Insulation Boards Opportunity An Delongchamps Writes To
The idea of dry-lining is highly familiar in Ireland, where for decades, families attempted to warm up their freezing outside walls, often shoring up a range of damp issues with a shallow timber frame, stuffed with fibre-glass batting, disguised behind plasterboard. The results were often catastrophic, leading to condensation issues and rarely improving, in any lasting way, the heat retention of the building.
In solid stone walls, typical of a cottage and many early farmhouses, dry-lining suffocated the property’s ability to “breathe” through its walls. It’s cheering to see renovators now tearing down these ropey improvements, following up damp troubles to their source, and putting in appropriate traditional French drains and insulation materials that can neatly and naturally wick moisture through the building.
Keep in mind that where you have cavity walls, cavity fill is the most cost-effective, non-intrusive way to improve their insulation value. The cavity was put into the house for a reason, so talk to an engineer to ensure it’s an appropriate improvement for your building. Only an energy survey (a BER assessment would be a good start) can indicate if dry-lining and/or cavity fill is a good place to place your investment.
Generally, dry-lining is suited to both solid block, cavity block and timber framed walls, and it can be carried out on all, or part of the building. It’s particularly suited to houses like my own timber-framed house which has a timber plank finish that would not take external insulation or cavity fill. Internal insulation won’t alter the exterior appearance of the property, something that will be important in a conservation area or where you have say a lovely existing wood, brick or stone finish.
More affordable than EWI (the exterior wrap), SEAI grant aid is only available if you’re doing the whole house (every external wall). You can also direct part of your Vacant Property Refurbishment grant to dry-lining as long as you’re not also applying for payment with the SEAI. With the SEAI, the grant amounts to as much as €4,500 for a detached home. Windows and doors on external walls must of course be insulated to a high standard too, or they will just provide a conduit for draughts and heat loss, so watch those ancillary costs. EWI, dry-lining and cavity fill are not there to solve chronic damp issues. These must be addressed before or during the work.
So, in its simplest form, dry-lining involves fixing dedicated insulation boards (polyurethane, polyisocyanurate-based) to the inside face of the external walls, over existing plasterboard or in some cases onto newly installed battens. In the past, these were then covered with a vapour control layer, plasterboard, skim and finished with paint as usual. Products like Kingspan’s K19 insulated plasterboard offer an all-in-one solution with the insulation and vapour barrier in one board. These boards can even be slipped up onto rafters in loft conversions and can be used between rooms to prevent the transfer of energy and noise from room to room. Internal insulation can also act as an acoustics barrier, together with good double or triple glazing, deadening noise from outside if you live on a busy road.
There are various modular dry-lining systems and the advantages should be explained to you by any supplier vying for the work. Homeowners are required by the SEAI to install wall insulation achieving a U-value of 0.27 W/sq m/K. This is what should be on offer from any supplier/installer on the SEAI register.
KEEP the old building saying “build tight, ventilate right” at the front of your mind. Your installer should take a special interest in promoting adequate ventilation to make the best of increasing and physically tightening up your home’s insulation. When any chronic damp issues have been sorted, the dry-lining system is working and there are enough air exchanges in the rooms, the walls are now deemed “warm”.
Condensation should be a thing of the past, without dribbles of moisture gathering on the inside of windows for example.
Layering on of insulated plasterboard increases the depth of the wall, and therefore eats up a small amount of internal perimeter in the room. It’s not a huge loss, but what makes it a bit tricky, is lifting, shifting, and reinstalling the various stuff that’s on the walls being insulated. This might include kitchen cabinetry, electrical outlets, plumbing, tiling, skirting and more.
Another caveat to keep in mind is Part L of the Building Regulations (2019) which impacts internal and external insulation measures. After any alteration to a minimum of 25% of your home’s surface area, your home must achieve either a minimum B2 BER rating or your heating system and attic insulation comply with the building regulation standards. You really would hope, after spending this kind of money that a B2 BER was easily within reach.
Some householders will prefer to have their dry-lining work carried out on a room-by-room basis to ease the pretty hairy domestic disruption. Talk to your installer about what’s possible. Just ensure that you finish within the time allotted as a condition of your grant, to avoid problems claiming back the money from the SEAI.
Don’t start work until you have grant approval. Things may turn up during the course of any structural work on an older house, so always put away a contingency fund for the unexpected. In a vintage timber frame home, you might want to take the existing plasterwork down and add a higher spec of insulation into the frame while the house is being torn open. It’s a rare opportunity. Otherwise, with the wind at your back, 15% will cover standard, little gnarly surprises demanding remedial work in a solid building.
- See seai.ie for further information