Insulated garden room or concrete garage

[hst forever]

Hello forum members just after some advice .I have been considering a insulated garden room  size 1.8 metres by 2 metres to house a small end to end layout and workbench for all year round use.My other alternative is to insulate a concrete sectional garage which is 8 foot by 16 foot and build a tailchaser layout.The garden room would be around £8000 with electrics to house.Garage already has power and light to main fuseboard in house(full house rewire done in June).Am I  wasting money in the garage option no matter how much I spend.The garage does need a good clearout as it is being used for storage after the house rewire.Garage is separate from house at end of driveway 

Edited November 14, 2019 by hst forever
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[hayfield]

I converted the garage at my previous house, my only regret was not to extend the central heating into it.

 

if you have an £8,000 budget go the whole hog and fully insulate it, add it to your central heating system and if possible integrate it into the house.  This way it will increase the value of your house, best of all make a dry, warm comfortable room to enjoy your hobby in.

 

We moved house 3 years ago after costing an outside workshop/layout room we just added it to the extension we were going to build. Acquisition cost neutral, heating far cheaper and much better security

[wasdavetheroad]

A garden room 1.8 metres by 2 metres (6 feet by 6 feet 8 inches) costing 8 grand -eek. The garage is over 3 times bigger

[doilum]

Definitely concrete garage. Don't forget to put in a raised floor. This is not only nicer on the feet but it insures against a torrential downpour causing seepage at the foot of the panels. If water ingress might be a problem due to sloping topography, you can "tank" the lower parts of the walls with bitumen paint. For the raised floor use treated 3x2 and "green" bathroom grade chipboard. If you have access to a large van or trailer there are real bargains to be had in insulation panels and sheet material. Assuming you do your own installation, I would think that £1000 would be a healthy budget.

One day I will clear the junk and fully floor and insulate my 29x16 that cost well under £5K using recycled concrete panels.

[Wheatley]

8 grand will by you more Kingspan and cladding than you need to insulate the garage, and a heater. And probably a few locos too.

[Harlequin]

If you insulate the garage be careful about how condensation is handled in the design. It’s an old chestnut that crops up here every now and then.

[hayfield]

If you can insulate the floor plus the ceiling. you are both keeping the cold out in the winter and heat out in the summer, If possible replace the door with a wall and window

[chris p bacon]

If it is a concrete sectional garage I wouldn't spend much money on it.  

 

You will need to vapour barrier the walls and add insulation to the inside  (min 50mm preferably 75mm) in a stud framing with a board covering (ply or plasterboard). You will need to create a damp course over the floor as concrete pads for these buildings are just a large slab. On top of the damp course membrane you will need more insulation and a floor surface (chipboard) 

 

What is the existing roof covering ? Garages such as these generally have a fibre cement board which has a useful life but as these garages aren't poular nowadays has most likely been there for some time.  If it has staining on, it will need changing to a modern equivalent as it's most likely failing and absorbing moisture. To use for a habitable room it will also need a breathable membrane underneath.

 

Another issue with these garages is the internal headroom, for a car just over 6 feet is plenty, but as you'll need to raise the floor by 3"  and will need to insulate the underside of the roof you could be down to 5'6"/5'9"

 

I did see an example of one of these garages converted approx 12-18 months ago, it had been done well but the lack of free flowing air on the rear of the sectional panels meant there was a build up of moisture, this permeated the concrete and has made the steel inside rust and blow the panels apart. It's likely the lot will have to come down in 1-2 years.

 

Personally £8000 for a small insulated shed is far too much, I would look at getting a local carpenter to build a timber framed & insulated shed for a third of that figure and possibly larger. 

[mikeg]

For less than £5000 you can get a 4m square log cabin and with the change have a new insulated base installed. 

I have a friend that has done this and it includes the erection cost of the cabin, it’s also more secure than a timber shed and being 40mm thick does not need insulation. I think that the one my friend has just uses a greenhouse safety heater for background heating and a fan heater this time of year when actually running his layout.

 I think that the supplier was in Bedfordshire somewhere.

 

 

 Regards mike 

[DCB]

You can get a double stable around 12 X 24 within an £8000 budget. We are acquiring one for Parish Council storage and its around £ 5500 so far including concrete base, but excluding electrics.  Might not even needs Planning Permission from the Jobsworths.  12 X 24 is a good space, even 12 X 12 is if your kid/ wife/partner  decides they want half to keep a pony!

[Nearholmer]

I would advocate that you discuss the concrete garage option in detail with Martin here https://www.rmweb.co.uk/community/index.php?/topic/135768-nether-madder-and-green-soudley-rly/page/62/&tab=comments#comment-3732732

 

Hiscexperienceviscrelated in his thread, and has been rather mixed.

 

My experience of wooden sheds is that, to use the old adage, with dry feet and a dry head they last very well indeed ..... my current one would probably last even better if I gave it a “birthday” in the form of a coat of preservative!

 

[APOLLO]

I bought my existing concrete garage in 1982. I dismantled and moved it to my new house in 1994 and it is still in very good condition.

 

What I did (on both builds) was to make simple frames of 2" x 2" timber nailed up, fixed to all sides, end, and roof into which I inserted 2" thick polystyrene sheet. The whole lot was lined with 1/2" insulation board then painted blue. On moving only some of the insulation board needed replacing, all the frames and polystyrene are original from 1982. An electric fan heater soon gets it warm this time of year. Floor is just painted concrete - yes cold but I have some rubber mats to stand on.

 

Regards sealing, I put mastic in the spaces where the wavy roof sheets rest on top of the concrete panels. Every joint concrete to concrete was double sealed with clear silicone, as is the panel to floor joint. I've NEVER had a problem with damp / water ingress even in the worst weather.

 

The glass windows (original) were simply "double glazed" utilising twin walled polycarbonate sheeting. This has insulation and security advantages. For security the doors are connected to the house alarm as well as it's own individual alarm. Lighting is by two twin 8'  fluorescent lights. These will need replacing soon with LED battens as 8' tubes are virtually impossible to find now - Thanks EU !!

 

Building again I would go the same route. Very little maintenance, just the doors and soffits / gutters.

 

Hope this helps,

 

Brit15

 

 

Edited November 15, 2019 by APOLLO
typo

[doilum]

Much of the "condensation" problem is down to the roofing material, in my case Onduline. The manufacturers have plenty of advice. The trick is a false ceiling of 5mm ply that allows the air to circulate on the underside of the roofing sheet material. This false ceiling could have a layer of insulation glued to the underside of the ply.

My man cave has a small 10x8' modelling room with simple 12mm chipboard sheets over 2x1 battens and a raised chipboard floor. A fan heater takes a few minutes to get it toasty. It also boasts double glazed windows on adjacent sides providing valuable natural light to the modelling bench. Now I have finished messing with cars I need to think about upgrading the whole cave.

[chris p bacon]

16 minutes ago, doilum said:

Much of the "condensation" problem is down to the roofing material, in my case Onduline.

 

The condensation is down to our breath and the difference in temperature between the outside of the roofing sheet and the inside.  As the top of the sheet is cold the warm air will condense on the underside.  This is why we Put a vapour barrier and insulation between the underside of the roof and the room.

[wasdavetheroad]

I had my garage railway room fitted with a 'warm roof' which is made up of plywood,extruded polystyrene, vapour barrier and the waterproof roof covering. the walls and floor are also insulated. there is no condensation because there are no cold surfaces

[doilum]

3 hours ago, chris p bacon said:

 

The condensation is down to our breath and the difference in temperature between the outside of the roofing sheet and the inside.  As the top of the sheet is cold the warm air will condense on the underside.  This is why we Put a vapour barrier and insulation between the underside of the roof and the room.

To be fair, excluding periods of snow fall I have never experienced a condensation problem  in any part of the man cave. It does require a great deal of heat before I want to work there once outside temperatures fall below 5C.

[hayfield]

I had a brick built garage at my last house, which on 2 walls was either single skinned of garage door. I built 1 stud wall and framed + insulated the other, false wooden floor but failed to insulate the ceiling. It had a newish efficient central heating boiler in the room.  In the winter it was still cold !!, as this was a temporary solution (I gave up a nice warm bedroom in order to sell the house) it was fine but had I stayed been staying at the house I would have done the following :-

 

1 Insulate both the floor and ceiling and perhaps thicker insulation **

2 Connect a radiator to the central heating system

 

What I did certainly showed no signs of damp, but was expensive to heat to a comfortable level

 

But the little I spent on it certainly paid off, whilst it could not be sold as a habitable room, the buyers recognised its potential as a music room for their children. We both sold the house very quickly and at top dollar, some of this was down to the housing market at the time, but our neighbours next door who's house was in a very similar condition sold theirs for less and it took longer. Mostly down to luck, but the few hundred £'s it cost certainly helped. Not forgetting the super advice from Crispy Bacon whilst doing the project.    

 

I realise you garage is totally different to my old one, which ever route you take ensure its properly insulated, and of course secure

 

** The house we bought we had a large extension built including a railway room, instead of installing a shed outside, (the cost being much the same either way) I was amazed at the thickness of insulation in the floor, walls & ceiling, but now realise its benefits

[Jol Wilkinson]

Keeping cost down is important but it is worth considering the longer term aspects such as effect on property resale value, etc. as Hayfield points out. Even then £8000 for a garden building of that size seems far too much.

 

I have been looking at various options ahead  of a planned house move, including those shown in the link below, starting at £1000 m2, including foundations, insulation, electrics, etc. Such a building would probably add value to a property, rather than having no benefit or even being a disincentive for future buyers as a converted garage or large DIY workshop might be.

 

http://www.thecedarroomltd.co.uk/portfolio/index

 

Losing the garage, even if it is probably never used for it's original purpose would be a no-no for me, given the secure storage it can provide.

[Paul13]

I have a concrete sectional garage that was converted to a railway/hobby room 3 years ago.  The main door was removed and replaced by new concrete sections, a new upvc door and double glazed window out in.  The original asbestos roof was replaced by a new insulated metal profile roof. The floor has a bitumen dpc layer on the original concrete pad and new concrete layer over this.  The walls have a vapour barrier membrane, foam insulation panels and are ply lined. It is bone dry and heats up nicely with an oil filled radiator. It is fully wired with it's own consumer unit. It wasn't cheap but is a solid structure and usable all year round. Well worth the investment I think and much cheaper than an attic conversion.

[johnofwessex]

My brother has a 'log cabin' garage he uses as a workshop.  He fitted a heat pump which seems to work OK

[Right Away]

Remember to seal the garage floor and exposed wall surfaces to minimise dust.