# Installing a solar vent in conservatory roof



## Woodchips2 (3 Jul 2010)

The solar vent in our conservatory roof has packed up and with this scorching weather the temperature inside is very high so I've bought another solar vent. This requires a 120mm diameter hole in the twin-skinned polycarbonate roof which I'd like to cut insitu (the old vent was rectangular so I cannot use that opening). I am thinking of cutting the hole with a router and an MDF template but are there any problems using a high-speed router on polycarbonate? Alternatively I could use a jigsaw with a template or maybe freehand.

Any advice gratefully received.

Regards Keith


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## Lons (3 Jul 2010)

Hi Keith

Are you sure the poly is twin skinned? if so, then it's probably only 10mm thick. Is it not triple (i.e. 16mm)
Most current roofs are multiwall and the majority of those I now fit are in excess of 25mm.

You'd have to be careful using a router IMO unless it has speed control as if you linger in any one spot you're likely to generate too much heat.
the polycatbonate sections are thin and easily cut with a jigsaw, fine tooth padsaw or even a very sharp knife.

you will gererate swarf and this will fall into the flutes and also be attracted by the static electricity. When panels are cut prior to manufacture of the roof they are "blown2 out with dry  air and taped. You will need a powerful vac and fine nozzel to get most of it out.

you won't have any problems but don't overtighten any screws and remember to oversize the hole to allow for expansion.

Bob


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## Woodchips2 (3 Jul 2010)

Thanks Bob, yes it is triple not twin. My router is single speed (20,000rpm) so I'll not use that. I'll try the padsaw first and thanks for the tip about allowing for expansion.

Regards Keith


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## stevep (4 Jul 2010)

Maybe use a holesaw ?


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## Jonesy (4 Jul 2010)

As it's plastic you might be able to cut through it with a hot blade - some soldering guns come with a plastic cutting/melting attachment for cutting sheet plastic.


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## Lons (4 Jul 2010)

Jonesy":1r65328w said:


> As it's plastic you might be able to cut through it with a hot blade - some soldering guns come with a plastic cutting/melting attachment for cutting sheet plastic.



Good idea but I think the heat will distort the edges and may be difficult to seal the vent.

We used to sell the stuff and I've handled it extensively for 25 years.
While it's polycarbonate, with all the strengths the material posesses, the walls are very thin and the strength exists soley because of the way the walls are linked. i.e.box / tunnel. They are not joined mechanically but the sheet is extruded as one continuous piece and just cut into lengths.

very easy to cut each wall with a stanley knife, easy to scratch or damage - just need to treat it with care.

*Keith:-*

If you're concerned, go to a couple of conservatory companies or look for a semi-finished plastics wholesaler (Amari Plastics?) and you'll get a sample or offcut to "play" with.
C&A Plastics ( www.cabp.co.uk ) might send you free samples, or www.livsupplies.co.uk
If you're really stuck, I'm sure I could find you some in my workshop.

rgds

Bob


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## Woodchips2 (15 Aug 2010)

Thanks guys for all the advice.

Have now completed the installation and cut the hole with an electric jigsaw after marking the polycarbonate with a felt marker pen from a cardboard template. Allowed for expansion as recommended and the vent is working very well. Had a torrential downpour yesterday and no rain came in!

This job was far more difficult in my mind than actuality. From start to finish it took me about 30 minutes whereas the 'planning' lasted days!!

Regards Keith


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## Lons (16 Aug 2010)

The Eriba Turner":2nwl50w9 said:


> This job was far more difficult in my mind than actuality. From start to finish it took me about 30 minutes whereas the 'planning' lasted days!!



Much better than the other way round though and definately the right approach if you haven't done it before :!: 

Always a relief after the first heavy rain and you don't need to run for a bucket :lol: 

Bob


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