drywall – Alt F4

This is pretty esoteric, right? I mean it probably ranks right up there with plywood vs OSB or MDF vs solid wood trim in terms of excitement factor. Since I had some issues using both, I actually did some research about the subject myself.

This is the advantage of a scattered and lack of focus blog is that I can just write about whatever I am doing at the time and try to make it seem interesting and that I am an expert. Well folks, if you are reading this either I am an expert (to you) or you are desperate for this very important decision, so let’s get into it.

Drywall became a product in the 1950’s to replace plaster. It came into common use in the 1960’s and there is no looking back. It seems like some specific areas of the country still use plaster (over a backer board like drywall) but it is drywall for most of us.

The primary advantages of drywall are that it is inexpensive, quick to hang and is fireproof. The paper backing will burn but not gypsum (the white stuff). The disadvantages are that it is not waterproof at all and will support hazardous mold and mildew growth with continuous wetness. Also, doing a nice job of finishing requires some skill.

In my area of the country, drywall is finished with a texture to hide the lack plastering skills (or making smooth walls). Other areas of the country, it is more prevalent to see smooth finishing. What we are most concerned about in this post is the seems where two pieces of drywall meet. Tape is put over the seems to cover any gap if the drywall panels expand and contract with temperature and relative humidity.

Conventional wisdom says paper tape is the first, best solution. It is cheaper than the fiberglass tape and seams to be easier to work with. You start by putting a mud bed, the width of one putty knife, I like the four inch knife. It is said that as that panels move behind the tape and you get a more consistent smooth finish.

In the picture above, the paper tape was incorrectly applied without the mud bed behind the paper tape. This has led to the tape pealing off over the years without adhering to the drywall. I have made the repair by adding new tape and top coat. I will use a wider knife (6″) for the next layer on top. The third pass if there is one will be an 8″ knife. You keep building successively wider knives and passes until the the tape disappears.

In this picture you see another manifestation to the same fault. A crack has developed where the paper tape edge transitions. Again, the mud bed was not set behind the tape creating a gap.

Fiberglass tape’s best use is covering gaps. This material is much more rigid and all the grooves allow you to press mud into the tape. I have found that it takes thicker passes to cover the fiberglass adequately, but it does do the job of covering smallish gaps, like less than 3/4 of an inch.

In my bathroom that I just completed, the contractor used fiberglass tape exclusively and it came out great. So, it is not that it can’t be done but I think it takes more experience to do a nice job.

The secrets that I have learned are as follows.

Do not overwork knife when applying joint compound. Less is more because you can always add more later.
When using wide knives, work the joint compound out of a tray rather than the container you purchased. You need to be able to continuously scrape your knife edge clean and get an even layer of compound on the knife. That can only be done when you container is big enough to hold the knife.
Big, blobby mistakes can be sanded down but it is a dusty mess and surprisingly a lot of work. Use a sanding screen rather than sand paper to do this job. Screen is found around the sandpaper in stores and doesn’t clog nearly as quickly.
For texturing, I layer a bed of joint compound and then dab at it with wadded up plastic bag. I then knock down all of the dimples with a clean trowel or knife to get the effect.
Don’t feel bad if you are intimidated or don’t get it right. This takes practice to do a nice job. I have only recently gotten the confidence to do whatever, whenever. I used to do everything possible not to disturb the drywall for fear of finishing failure. Now, I find it easier to cut out a whole wall if it will make it quicker to do a job.

So, you see the answer depends on the situation. Both can work and both have advantages with different variables.