Is this sealed ceiling OK to build?

[Udhi]

Hi all,
I have an EPDM flat roof in my new workshop. The perimeter of the roof is sealed against the elements. EPDM is laid on 18mm OSB. Joists run the 5m length and noggins in place in between.

The roof with the current joists and noggins exposed is affecting light levels. I was thinking of installing tongue and groove OSB to them to give a smooth "ceiling" which when painted white, promises a step up in available light.

I think I would seal the roof, if I do this and stop air circulation. Can I still do this if I make a 25mm hole in each noggin and joist and install a similar hole in each OSB sheet making the ceiling? Essentially ventilating each sealed "box" where the joists and noggins meet....

Hope this makes sense!

 

[Udhi]

Anyone? Am I worrying the gentry in here with cowboy techniques or is my post above not making any sense?

 

[catlad]

If you are wanting to clad the underside of your joists in timber then no problem but it sounds like you need a couple of skylights to me.

 

[Udhi]

Thanks for your reply.

There's the potential for a lot of light; two tube lights and windows. Installing a white ceiling would provide provide a good reflective surface to make the best use of all this light?

I was told once that applying chipboard as a ceiling would cause damp or condensation in the void due to loss of circulation. I just want to know if this is possible?

 

[ree]

What kind of flat roof is this - cold or warm?

What do you mean "the perimeter of the roof is sealed"?

Irrespective, all flat roofs are "sealed" with a moisture/vapour barrier from below. You dont seem to understand the construction detail of a flat roof - research pics on google.

Who built your roof?

 

[Udhi]

By this description, mine will be similar to the cold roof, but it has no ceiling or insulation.

Perimeter sealed: the edge of the roof meeting the walls are sealed water tight by way of osb boards and UPVC fascia boards. Unlike a corrugated roof in another garage which has open air gaps between the corrugations and the wall so it is unsealed and fully ventilated.

There is definitely no seal as you describe it, in this roof build. Working from the outside; we have EPDM, glue,OSB,joists and noggins.

A couple of guys who have built their own sheds did mine as part of an agreement. No builders or roofers were involved.

 

[ree]

I should simply go ahead and underboard as advised above.

 

[Udhi]

Would that not stop air circulation? Because the joists are closed off with noggins, I thought I might sealing each " box" (made up of two noggins between two joists) with the ceiling board?

I was wondering if circulation is important and if it can be restored by drilling two 25mm holes into each noggin and joist?

 

[tony1851]

Unless you are incorporating a swimming pool in your workshop, you are over-thinking the issue.
Just underboard it in anything you want.

 

[Udhi]

Happy days. Ree and Tony, Thank you for taking the time to answer.