Edna, drywall blisters usually occur due to several reasons. One being, there is a minimal amount of evenly spread or even total lack of drywall compound between the tape and the drywall surface. The rule of thumb is there should be 1/6 of an inch of drywall compound. It is possible your husband is not using the correct drywall tools. Our guys like to use a 6 or an 8 inch wide taping knife, however there are a variety of tools that can be used for different drywall applications. The percentage of these blistering issues created by cold wet weather is pretty slim, so I tend to think it is a matter of inexperience, but I commend your husband for trying. It is possible that the drywall compound could have been frozen and not fresh, which would create these blistering issues. We have seen many cases where husbands remove too much joint compound from under the taped area. The blisters are formed when the tape absorbs the moisture from the second application of compound. The drywall compound “swells” and because there is not enough compound under the tape, air bubbles are created and the tape has nothing to hold it flat. Drywall repairs are an art and drywall finishers know when to add water to the compound, they use the right tools and know how to center the tools and not tear and put too much pressure on the tape. Another cause of the blistering could be from condensation if the area is not allowed to dry properly, and if the area is painted too soon and not allowed to dry, water is retained in the sheetrock material. We are here to help and make your life easier.