What are your input systems?
Oh the headaches this one has caused me…
The first thing to determine is which is your over-riding goal – keeping costs down or be ‘green’? With mains gas still the cheapest option (at least in the short term) a modern gas boiler is probably still the best choice if you’re on the mains and cost is a priority (and arguably it’s not so bad on the green-front as other electricity hungry solutions – but I’ll not be having that argument with anyone thanks very much!). With no mains gas we get into the standard set of barn conversion options – oil boilers, heat pumps (ground and air source), combined heat and power (CHP), bio-mass (& 2) and conventional wood burning.
Oil is expensive and looks set to get more so, heat pumps consume electricity (again expensive and looks set to get more so, add PV to generate your own and push up those capital costs even further), CHP may still be too young as a technology (although it may be interesting when used in combination with mains gas in something like the Baxi Ecogen micro-CHP unit) and bio-mass / wood burning are only really suitable if you can ‘grow-your-own’ or at least have a ready supply of firewood and a love of chopping logs (unless you fancy burning pellets and tying yourself to the vagaries of that budding marketplace). I said it was a tricky subject…
I reserve a separate paragraph for solar thermal hot-water as I feel it deserves to stand-alone. Unless you’re really, really pushed for budget, I see solar thermal hot-water panels as an essential feature of any contemporary build, regardless of which other choice(s) you make when building your space and water heating solution.
Those are your options, take your pick…
Don’t forget you should minimise your demand for heating, so maximising your levels of insulation and the solar heat gain from good passive solar design is just as important as your space and water heating solution.
… Rooms – what, where and why?
I think in the UK we take a strange approach to consideration of houses, judging a potential home, first and foremost by reference to its number of bedrooms. Forget the rest of the space and all the other essential functions of a home, just think bedrooms…
Early on in your design it’s essential that you take a step back and consider all the purposes that the space under your roof needs to accommodate and the ways in which this can be achieved without allocating a specific room to each.
For example, the second bedroom at the barn will accommodate a cabin bed, a desk and a bed-settee thus allowing it to function as my son’s bedroom, a study and an occasional guest bedroom – 3-in-1!
… floor levels are dictated by a heady blend of building reg’s, foundations, ceiling height and final finishes – you need to consider each of these – tricky!
What goes into the floor? Literally – hardcore, sand, insulation, a damp proof membrane – in many parts of the UK this will need to also be a radon barrier membrane, then the concrete or limecrete slab (more below). You should also consider slipping under-floor heating (UFH) cables or piping in there. Admittedly, UFH costs more, but it provides two things I like – no radiators and radiant heat (even heating throughout the room – no hot spots / cool spots and lovely warm floors).
As a slight aside, if you install under-floor heating ensure that you use appropriate materials when installing your finished floor – an appropriate adhesive for tiling or kiln dried (bone dry) wood. This will add extra cost but is essential.
The limecrete or concrete question is still one that is open to debate in my mind. Undoubtedly, there are environmental and ‘healthy house’ benefits from using lime. However, it’s also more tricky and expensive to use, is different from concrete (and therefore needs to be ‘understood’ by those working with it) and is more sensitive to weather conditions. My position is to use lime if the three B’s line up – that is, if the Build, the Builder and the Budget all allow or encourage the use of lime then use it!
For the record, we didn’t use limecrete at the barn.
…for a conversion your hands are usually tied but you’ll need to consider insulation, finishes and any remedial work.
First things first, will the walls remain or do they need to come down? I’m going to assume they will remain as afterall, this is a site about CONVERSION…
Some questions to be answered…
Will some areas of the walls need rebuilding? Will you need to underpin some sections of the walls for greater stability? Do you have cracks in the wall that will nessitate restitching or partial rebuilding?
Pointing – (mortar not fingers) will your walls need repointing? If so with what materials? You may need to research the original construction techniques and materials so that you can achieve a sympathetic result.
Insulation. Don’t forget that insulation can be placed both internally and externally in the form of render or cladding. External insulation can be a great way to avoid losing internal space.
Rendering, painting or washing. Is there any reason, cosmetic or practical that you may need to apply a covering to the wall. For example, I had the end wall of the barn rough pointed and whitewashed in a attempt to increase water tightness.
… construction material, requirements for attic space?…
Consider the following: Do you need to replace the roof?
The answer may be a resounding and obvious YES – you may have holes as large as tiles or a ridge line like a camels back. But there are more subtle reasons to replace a roof. To conform with insulation and ventilation related building reg’s, to get the attic space you need or to accommodate the solar or PV panels you intend to deploy, it may be easier, quicker and cheaper to replace, rather than fix up the existing roof.
Keep an open mind.
Protect your heritage
One aspect of the roof that I would retain where possible are the original roofing materials. The welsh slates I’ve kept are far superior in terms of durability and appearance to the more cost effective modern materials I would have likely had to use if an entirely new roof had been required.