Downlights in Vaulted PIR Ceiling

[richo106]

Hi All

 

We are having a couple of vaulted ceilings and a flat ceiling area in our renovation project, SE has spec'd 175mm Joists

 

Insulation has been spec'd to be 120mm PIR in between joists and then 50mm PIR backed plasterboard.

 

What is the best method to install spot lights in this situation?

 

All advice/information appreciated, I am a qualified electrician but never installed spots in PIR before and want to maintain insulation level etc

 

Many Thanks

[ProDave]

Spots in a sloping vaulted ceiling point the wrong way.  Fitting them compromises the insulation and air tightness and does not give the fittings adequate ventilation.

 

I fitted individual surface spots that you can angle to any direction you want.

[Conor]

Batten out a service void on the underside of the ceiling on top of the vcl/insulation. 50mm should be enough, though fire rated ones might need more.

 

So basically instead of 50mm insulated PB, you use 50mm PIR across the joists airtightness etc, batten after, run all your services in this void then board. 

[richo106]

45 minutes ago, Conor said:

Batten out a service void on the underside of the ceiling on top of the vcl/insulation. 50mm should be enough, though fire rated ones might need more.

 

So basically instead of 50mm insulated PB, you use 50mm PIR across the joists airtightness etc, batten after, run all your services in this void then board. 

Glad you said this, this was my original thinking. I will get the downlights before so I know exactly what size void I need to create

 

Many Thanks

 

 

[Conor]

The cheapest way I could figure out how to do it (couldn't find 50x50mm timber) was to use standard cheap 22x50mm battens fixed in with suitably long screws, then another batten fixed on top with nail gun.

[Conor]

Just now, Conor said:

The cheapest way I could figure out how to do it (couldn't find 50x50mm timber) was to use standard cheap 22x50mm battens fixed in with suitably long screws, then another batten fixed on top with nail gun. Think we needed 600m+ of the stuff. Not a fun job!

 

[saveasteading]

3 hours ago, ProDave said:

Spots in a sloping vaulted ceiling point the wrong way.

They are available with a tilting feature. Have had them from TLC (which were used on a sloping soffit) and from SF simply to be adaptable in a kitchen.

Whether the tilt is enough for your circumstances you would have to check.

 

As above...some units are very shallow and others remarkably deep. Catalogues' spec's should say.

[richo106]

8 minutes ago, saveasteading said:

They are available with a tilting feature. Have had them from TLC (which were used on a sloping soffit) and from SF simply to be adaptable in a kitchen.

Whether the tilt is enough for your circumstances you would have to check.

 

As above...some units are very shallow and others remarkably deep. Catalogues' spec's should say.

Yes they can vary quite a lot in depth, fortunately these are for upstairs bedrooms and landing area so not required to be fire rated which might help. Saying that most of them are generally fire rated now

 

[wozza]

Our extension roof (vaulted) had 100mm PIR between the joists and 75mm under.

 

I created a service void using the MF Ceiling system (Metal frame) its really easy and something you can do yourself.

 

We boarded over the top then used Aurora angled downlights (that can split in half to reduce the depth).

 

 

[saveasteading]

Forgot to mention that tlc sell some with optional lenses to change the angle of light spread. Useful with low or high ceilings, to get an even spread.

[Gone West]

1 hour ago, saveasteading said:

Forgot to mention that tlc sell some with optional lenses to change the angle of light spread. Useful with low or high ceilings, to get an even spread.

+1 I bought some of those from TLC in 2014 and they had three or four different angle lenses which was very useful.