Loft Climate Advice

Can I get some advice from those of you that have not had full loft conversions but still use a loft for rec. In my case it's model railroading...

I have a large layout (just track & stock only atm) in my loft which is a modern truss roof with a layer of black cloth type material between the roof spars and the tiles on the outside.

My problem is probably a common one: Temperature.

In the winter with a small electric heater and an open hatch I can keep temperatures to above 5c at worst overnight and make them habitable during the day. It's during summer I have the problems. Temperatures will reach 40c up there on the warmest days and I am concerned about long term damage to stock and buckling of track, not to say it is totally impossible to work up there at those sorts of temps.

My options seem to be

1) Roof light to let heat out. Expensive and may not work well enough to be worth the outlay. Plus I have to remember to open it !!! 2) Portable A/C unit but I read that the cheaper ones need good ventilation which I obviously don't have. 3) Some sort of insulation in the roof between the trusses to keep the temps down in summer and up in winter. Again, expensive and not a DIY option as far as I know. One loft extension company warned me that the material has to be a special sort to prevent the roof sweating.

I can't see any other options but has anybody else had my problem and actually solved it? I don't mind throwing a bit of money at it for a workable solution. BTW, dormers are out for appearance reasons and both loft 'ends' face onto the sides of other houses (we are a 3 bed detached).

I'm dreading another summer of hobbying in a sauna!

Reply to
Gary Brown
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Gary Brown wrote on 10/05/2005 :

An opening Velux style window would fix most of your heat problems in the summer. I have no idea what to suggest for the insulation problem.

Reply to
Harry Bloomfield

Could you install a couple of fans in the "ends" one end blowing out, and the other in?

I have no experience of doing this, but if they had enough flow, you would be blowing out hot air, and sucking in cold (well, outside temperature!) air

Maybe install multiple fans, keeping to the in one end, and out the other idea?

Sparks...

Reply to
Sparks

Velux windows even when fitted on both slopes of the roof do not adequately cool the loft. After many summers living in a loft and suffering unbearable tempuratures the only correct way is to stop the approx 6 kw per metre of heat reaching the inside of the roof. Celotex or Kingspan fitted between the rafters 50mm with air gap between tiles and insulation will work. remember to tape the joins to complete the job.

Reply to
sploop

sploop?? are you simple, or cant you read?

I did not suggest just using fans to stir the air as you blurted out, I suggested installing fans IN the walls, to the OUTSIDE of the building, one drawing air into the loft from outside, and the other blowing the hot air out the other end of the building.

Sparks...

Reply to
Sparks

In message , Gary Brown writes

Can you get automatic openers, like they use in Greenhouses I wonder?

how about a thermostatically operated extractor fan?

Nah, this sort of thing is quite DIYable, insulation slabs are fitted either between the rafters, or over them.Nothing special about the materials. You need to leave enough space behind the insulation for there to be ventilation to stop condensation that is all.

Don't know how effective it would be though at heat reduction.

I take it you mean gable ends. A decent sized extractor fan highish up in the gable at one side, with a vent in the other may help a fair bit.

Reply to
chris French

If you DIY, you could do it for 200 - 300 ish. Would probably help a fair bit.

AC would be most useful if you had some decent insulation in the first place. All A/C (good or bad) needs a place to vent the heat (and water)

- they don't generate "cold" as such - just pump heat from one place to another.

Expensive ish - depending on the size of loft you could probably do it very well for 400 to 600. or moderately well for say 200 to 300. Even moderate insulation would be a huge advance on what you currently have though.

Very much is DIY'able - not a difficult job.

The material is not that important (but rigid foil covered PIR Foam panels would be simplest to use), but you need to ensure that the roof woodwork can still get ventilation so that it does not rot. This may mean needing to install soffit and ridge vents if you fully enclose the internal surface of the rafters.

A window in one/both of the gable ends may work quite well - does not matter if the view is only of the adjacent gable, since what you are after is ventilation not a nice sunset.

Perhaps you should ditch the trains and install some nearly naked Sweedish lasses instead - may make the sauna seem far more appealing ;-)

Reply to
John Rumm

On Wed, 11 May 2005 02:42:04 +0100, John Rumm

Now that's the best selection of all.

Thanks for all the others, I was wanting to cover the inside face of the roof rafters anyway for appearance and to bounce to light around better. Was thinking about 6mm MDF painted white as being lightweight, easy to cut and shape.

Need to investigate the insulation material more though. I think that's my favorite option as it seems the most DIYable without cutting holes in any walls!

Reply to
Gary Brown

I'd kingspan the whole place, this is an easy DIY job.

Put the kingspan tightly between the rafters, leaving a 50mm gap at the back for ventilation. The ventilation gap needs to be exposed to the outside. You should have soffit vents so thay should vent the gap.

The more kingspan you can put in the better the job will be. You need to ensure there are no gaps. This will keep the heat out and in.

Kingspan can be cut with a bread knife, and just jamed into the gaps. No nasty rockwool type fibres to worry about either.

Rick

Reply to
Rick

Can you point me towards an explanation of sofit vents?

I'm assuming you mean the area where the roof meets the outside walls. I had always assumed there was sufficient ventilation there anyway as I can see daylight in a few places already (never been over that far, ingrained fear of spiders!!!).

Reply to
Gary Brown

The rigid foam types are the simplest to use in these cases. Trade names like Celotex, or Kingspan are often quoted. The web sites for these companies also have good information on their use for your application. The generic name is PIR or eurothane foam. Have a look at:

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Reply to
John Rumm

| \ \ __\ | ^ | Soffit |

i.e. the horizontal board that fills the gap between wall and edge of roof. Note that not all buildings have them - if you can see the ends of the rafters from outside of the house then you may not.

If your soffits are made from wood or PVC or something drillable then you can retrofit vents quite simply:-

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Reply to
John Rumm

that's "urethane" (unless you know of some new european variety)

Reply to
Tim Mitchell

I assume by modern loft, you have the W shape supports, and all the bits of timer look very small. These type of roofs work well, but you can't mess with them much before they loose lots of strength. A bit of flooring, and a railway track is not too much weight, but 6mm of MDF on the slopes might work out to be one heck of a lot more weight than you first imagine. If you do do this use screws, not nails, the vibrations of hammering are not always usefull.

The kingspan is sliver, any more than a strip light up there and you will need sunglasses. I am putting it on my roof, and its doing my elese in when the sun reflects.

Rick

Reply to
Rick

Firstly insulate.

2nd, install 2 fans or 2 windows and open them: the air will run right through. 1 isnt anything like as effective.

NT

Reply to
bigcat

sploop pretended :

Perhaps not, but from personal experience just one brought the temperature of my loft down to bearable levels in mid-summer even before the insulation went in. This depended on a good flow of air being drawn in from the rest of the house (window or door open).

Reply to
Harry Bloomfield

;-) thought it looked wrong when I typed it, but then got distracted before trying the spell checker!

Reply to
John Rumm

in my experience they make a dramatic difference, though there must be through flow. (For some reason people seem to want to arrange them to minimise through flow.) Whether its enough is another matter: on a 95 degree day, few things are enough.

NT

Reply to
bigcat

I was planning to use my electric staple gun which should have ample strength to hold the board if enough staples are used.

I doubt the weight is an issue, given that any roof has to be able to support >6" of snow without collapsing and snow is very heavy. Plus the weight is acting at a 45deg angle and is therefore reduced in the down direction as well.

The only thing I am unclear on is how far to go for vapour barrier purposes and exactly how to deal with this issue.

Reply to
Gary Brown

For the VB, take a look in the kingspan / celotex websites, they have some nice drawings.

Rick

Reply to
Rick

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