Pipe insulation

Is it necessary or useful to insulate not and/or cold supply pipes inside interior or exterior wall cavities?

The exterior walls will have the normal fiberglass insulation between the outside wall and the pipes and some of the interior walls will have fiberglass insulation as well for noise control between rooms.

I'm wondering if condensation on cold water pipes or heat loss on hot water pipes is an issue in closed walls.

I know people commonly insulate the supply pipes when exposed in an unfinished basement. Do they only do it there (basement) because they are accessible and would they do it everywhere if the pipes were accessible?

I have the opportunity of having all my plumbing walls open now and want to take advantage of the opportunity if it is a good idea. Don't want to waste time/money if it doesn't buy me anytthing.

Thanks,

Joel

condensation

Condensation inside walls tends to be a problem here in Florida because of our superior climate. As in hotter and more humid. You can find more ways for structural rot to start here than anywhere else I've ever been, and people here use T111 ply siding on a lot of houses, so condensation tends to cause problems there too. I have only anecdotal evidence, but I think if I was replacing any piping in my walls, I'd wrap it.
Of course, we have more termites, and bigger mosquitoes and cockroaches than even Texas.

Any exposed piping is a good candidate to insulate. In their wisdom, the builders of my place ran the water pipes near the duct work. They didn't seal the seams in the duct work, either, or insulate it. In the summer, the a/c was pre-chilling the water...made for a great awakening in the shower until it cleared plus put a bigger load on the heater...it had to be raised to account for all of the losses in the piping. When remodeling, insulate anything you can get to...it will help with energy loss and moisture problems.

Type of insulation

Thanks for the help guys. I will insulate away after the inspection.

One more question. What type is best to use? I've seen two "grades" of the foam/rubber insulation at the big box stores. I think one is about $2/piece and the other almost $4/piece and the material is differnet. I think foam for $2 and rubber for $4. Is there an advantage to a particular material?

I'm assuming fiberglass wrap is not necessary.

On a side note, I am thinking of using fiberglass wrap or bats in the cavities to deaden the noise from the PVC DWV. Will this work and are there other tricks to keep the noise down in the drains?

Thanks,

Joel

One factor to consider is that for insulating cold pipes you want something that is a good vapor barrier. Otherwise, you will get condensation within the insulation. The lower cost material is probably all you need, but on the cold water lines you should seal the joints with tape if you expect condensation. Condensation is usually a problem only when your water source is a well and you don't have air conditioning.

The black rubbery insulation is a different plastic that is usually used for chilled water lines and suction lines of refrigeration systems. http://www.polfrost.com/aeroflex/p_aeroflex.html