What are your experiences with insulating above headliner

[chowdan]

First off I want to thank EVERYONE for all their feedback.

I've seen a lot of threads on statistics and such, but I wanted this thread to be focused on real world experience, which will in turn help guide me to a decision of my own.

I'll have to take a look at rockwood for the fact that it is fire proof. Reflectix seems to be incredibly common and seems to be effective.

[Cpt Pat]

Originally Posted by tankersteve

Very interesting thread. What are the thoughts on adding insulation not to retain heat in winter, but to keep the interior cooler in the summer?

Tankersteve

Insulation does both jobs equally well.


And a radiant barrier (such as aluminum foil) has no effect without an air gap between the hot and cool sides (conduction without radiation). Aluminum by itself is actually the opposite of a thermal insulator - it's a good thermal conductor.

[chowdan]

Originally Posted by tankersteve

Very interesting thread. What are the thoughts on adding insulation not to retain heat in winter, but to keep the interior cooler in the summer?

I'm refitting a Cal 31 in Hampton Roads, and I have the headliner off to find leaks. I was planning to epoxy on some painted battens, and then use heavy duty velcro with some strategic twist fasteners to hold my new headliner in place. I have the ability to add a thin insulator between the battens, and was curious about recommendations.

Thanks.

Tankersteve

I would assume that if your boat has a problem with getting hot inside due to the decks heating(I imagine steel/aluminum, and possibly teak decks), it will likely help given that you have good airflow.

[Suijin]

Originally Posted by tankersteve

Very interesting thread. What are the thoughts on adding insulation not to retain heat in winter, but to keep the interior cooler in the summer?



I'm refitting a Cal 31 in Hampton Roads, and I have the headliner off to find leaks. I was planning to epoxy on some painted battens, and then use heavy duty velcro with some strategic twist fasteners to hold my new headliner in place. I have the ability to add a thin insulator between the battens, and was curious about recommendations.



Thanks.



Tankersteve

The Reflectix (available at Lowe’s in rolls) made a huge, HUGE difference in summer heat.

I’m not expecting to overwinter in a cold clime again and as I said Reflectix was chosen out of expedience. I’m sure some of the better insulators work better and are probably cheaper.

I would heed Bill’s advice pretty closely to get the best result. If I was going to be somewhere cold again I might open it back up and do it over more carefully.

[buchu]

Originally Posted by NevisDog

Yea 13mm Armacell closed-cell-foam insulation (non-flammable, used around air ducts in buildings) made a huge difference to amount of under-deck condensation, even in temperate NZ. Important to insulate around all those through-deck bolts holding winches and genoa tracks in place too. CSF is easy to glue to underside of deck/cabin but I sure wouldn't want any liners fixed permanently; I'd always screw them in place for easy access to wiring, through-deck fittings etc.

Dear NevisDog, I know this is quite an old thread, but we are in the process of insulating our boat woth Armacell and are unsure about or whether to also cover all the proud standing through-deck bolt fittings with it as we are using the self-adhesive product. Are you saying one should only indulate around it, not covering these? Or should one cover them with a separate section to be able to get off easier later? Thanks much!

[Oeanda]

I’m in the same boat as the OP as far as I’m currently plotting to replace the headliner, in probably much the same fashion, in PNW climate, etc. Reading this thread last night sent me off to google Reflectix. On their site they insist strongly on a 3/4” air gap between the insulation and, in this case, the hull.
Kind of inconvenient knowing about that air gap thing now because I’d been planning to glue it right to the fiberglass, as I’ve seen others do. But the difference in R value, doing it properly, looks pretty huge.

[mitiempo]

Originally Posted by Oeanda

I’m in the same boat as the OP as far as I’m currently plotting to replace the headliner, in probably much the same fashion, in PNW climate, etc. Reading this thread last night sent me off to google Reflectix. On their site they insist strongly on a 3/4” air gap between the insulation and, in this case, the hull.
Kind of inconvenient knowing about that air gap thing now because I’d been planning to glue it right to the fiberglass, as I’ve seen others do. But the difference in R value, doing it properly, looks pretty huge.

The bulk of the R value is the air gap. Reflectix has very small R value by itself.

Reflectix can be successfully used in conjunction with other closed cell insulation without an air gap.

If you leave the air gap you will get condensation against the cabin top where the warmer inside air comes in contact with the cold surface.

[Oeanda]

Originally Posted by mitiempo

Reflectix can be successfully used in conjunction with other closed cell insulation without an air gap.

Could you explain that a bit more? I am now thinking I’ll be putting some minimum amount of 3/4” spacers (I was thinking styrofoam) behind the Reflectix to help create the air gap and hold things in place reasonably well prior to putting up the headliner, which will probably be thin t&g cedar strips.

[mitiempo]

Originally Posted by Oeanda

Could you explain that a bit more? I am now thinking I’ll be putting some minimum amount of 3/4” spacers (I was thinking styrofoam) behind the Reflectix to help create the air gap and hold things in place reasonably well prior to putting up the headliner, which will probably be thin t&g cedar strips.

What I mean is you could layer the Reflectix with foam or other insulation but an air gap just gives condensation a place to form.

Remember that Reflectix provides virtually no thermal insulation. It is a radiant barrier.

[TeddyDiver]

Originally Posted by buchu

Dear NevisDog, I know this is quite an old thread, but we are in the process of insulating our boat woth Armacell and are unsure about or whether to also cover all the proud standing through-deck bolt fittings with it as we are using the self-adhesive product. Are you saying one should only indulate around it, not covering these? Or should one cover them with a separate section to be able to get off easier later? Thanks much!

Do the separate section. With any through bolt there a potential risk of small leak. What you don't want to happen is leaking go behind the insulation all over. So a separate section installed in a way showing possible leak instantly.

[DeValency]

My Contest original headliners (about 30...) are all covered with a 5mm sponge backed vinyl and I would recommend to do the same. The boat is designed for the North Sea...

Would not recommend to insert insulation above the liners, it can attract moisture and be on your way when you deal with the light fixtures, wiring etc. I like this area reasonably ventilated.