Charleston home inspector discusses general insulation requirements.

Yes for a ventilated crawlspace system R19 is required.  Withoug insulation the subfloor sheathing will get moldy and rot especially if the occupants like cool AC in the summer. Think of it like this. A nice ice cold glass of tea condensates on the outside of the glass. So this is what happens to your subfloor sheathing without insulation. If you like your thermostat turned down in the summer....the faster the damage will occur. If you install moisture resistant floor covering, then the AC won't be able to dry the subfloor out from the inside as easily....so the damage occurs faster. In the Charleston lowcountry area many homes can benefit from an encapsulated crawlspace system. Contact a professional about installing this type of system because special knowledge is required.

Thank you fo your question.  Modern insulation standards are enough for for attics in this area and the HVAC system should be sized and calculated by your HVAC technician based on the size of the home, insulation and other factors. There is a lot of science in this. If the builders are giving you a choice of insulation types then you may get different opinions from contractors based on their business model. My personal preferance is blown in cellulose applied on top of the top floor ceiling. It stays in place better than the blown in fiberglass ( which floats everywhere and tramples easily)  and it doesn't irritate my lungs when I crawl into the attic. Again my opinion here is to avoid foam on the underside of rafters (creating an encapsulated attic). In my opinion it serves no useful purpose.  Foam will hide the condition of the roof sheathng if there is a leak. Most roofs do experience a leak eventually. Without the drying effect of a ventilated attic a small leak can be hidden (behind the foam) and a lot more sheathing damage can occur. Also most of the encapsulated attics I've seen have had issues with moisture buildup in that space making a dehumidifier necessary. However this isn't discovered until after problems arise. Hope this helps......

My guess is that you're talking about duct work in the crawlspace.....My recommendation is to contact an HVAC technician so he can remove and/or re-insulate the ducts to modern standards. Condensation dripping from duct work means it isn't insulated well enough and depending on the type of duct,  replacement may be an option (metal ducts for instance could be rusted). Also wet insulation is not much good as long as it's wet and then there's the question of microbial growth. After the repairs are done there may be some benefit to spray foam in this instance especially at the boots. In general I'm not huge fan of spray foam. If this is a tight crawlspace placing a quality vapor barrier (6 mil or better) on the ground will reduce the amount of moisture in the air so will reduce condendation that way.

Hope this helps....

I apoligize for the delay in answering.

Yes install a vapor barrier on the warm in winter side of the wall. Sometimes the insulation comes with paper backing which acts as the vapor barrier. The edges of the paper are stapled through to the studs.  If not they sell thin pastic sheeting for this. Just staple it on. Hope this helps....

Thanks Eric....It is not necessary or desirable to have a vapor barrier on the ceiling in this area. Most attics have blown insulation directly on top of the sheetrock which is fine..... and the attic is ventilated so moisture can dry out via the attic. If you have to use roll insulation unfaced is better....if it has a paper facing it's ok but it must face the warm in winter side of the ceiling. On walls the paper facing is always towards the warm in winter side of the wall. Some bulilders will put a thin sheet of plastic up instead which is ok.

On floors some of the more modern simulated hardwood flooring products are very restrictive as far as vapor transmission is concerned. So if you have a crawlspace watch out. For instance the old fashioned hardwood floor over a crawlspace would allow drying from both sides. If faced insulation was installed it could only dry from the inside for the most part. Add the simulated hardwood laminate and now the subfloor has no way to dry out. Trapped by the paper facing on the insulation from underneath and either the foam backing or top coating of the simulated hardwood flooring above. For this reason a house can do fine for many years and then undergo remodeling with modern AC and laminate floor coverings and start to have problems with trapped moisture in the crawlspace. Anyway hope this helps....Ray

I would say most places on Johns Island would benefit from a vapor barrier installed on the ground. The lower the home (floor framing) is to grade the more important it becomes. As far as the paper facing on the insulation is concerned...in the crawlspace it can be eliminated...this can be considered if restrictive floor coverings (to moisture movement) is installed over the subfloor as a finish flooring. In my opinion anything that stops the natural drying process can trap moisture and cause moisture issues. The paper facing acts as a vapor retarder and sometimes moisture is trapped between the paper facing and a restrictive floor covering....add that to the desire to cool a modern home with air conditioning which exacerbates the issue. Each case if different so all options should be explored.

Thank you for your question.

My answer to this is my personal opinion based on my observations. I'm not a big fan of spray foam insulation (though I know it is marketed heavily) in wall, ceiling, and roof systems.  Under the roof it hides the sheathing which makes checking for leaks impossible.....leaks happen in most homes at one time or another and this leaking can continue until major damage has occured because not only is it difficult to see but the foam holds the moisture from evaporating as quickly. Also if your attic is unfinished it's a waste as the ceiling is the proper place for the insulation. I have inspected homes with spray foam under the attic rafters and those homes have needed a dehumidifier in the attic to control the moisture. Moisture is everywhere and in every breath we take. Proper home design takes this moisture from the ground, people, pets, plants, cooking, showers etc into consideration and allows for a natural process for this moisture to escape. With moderern floor finishes and air conditioned homes this process needs even more consideration. In walls moisture issues can occur too especially in areas where plumbing is located. I do like the application of foam in the crawlspace however just because it stays in place better. Though sometimes in a few instances it's application appeared a little thin. But again places were plumbing is located could be an issue if a leak developes. A small amount of water trapped in behind foam evaporates so slowly damage is amplified when it is finally discovered. The solution might be to stop the foam in places where piping emerge from under the floor for inspection purposes. Stuff some fiberglass in those places.

There also an issue with certain types of roof coverings, roof covering of all types do better if the roof deck is cool or can breath from underneath. The manufactures of wood shakes for instance advise against foam under the roof deck.

Controlling moisture in homes is a complex issue and caution is advised in any system which may stop the natural drying processes. Foam of all types can hinder moisture movement so you should take this into consideration.

The good thing about foam is it does appear to seal around penetrations etc. better. But even that is contriversial. Now that your house is sealed like a drum you'll want some make up air to breath.

Thank you....it's alwasy nice to hear a kind word....