You Can Skim Coat Rough Plaster Or Drywall ...Prep For Wallpaper Or New Texture

I really admire them as professionals, since many of them are excellent craftsmen. (Shoot, I can barely manage to wrap a Christmas present).

With few exceptions, the one thing they hate is having to hang wallpaper over rough or textured walls. They can hang a filler layer first, if they choose, to mute the coarseness of the surface, but this option is often not their first choice.

There is a better way to prepare the wall or ceiling for paper, but they would prefer this to be done for them ahead of time. This means skim coating the old roughness with new material to render it smooth, perfect for wallpaper.

So the call comes to me. I guess I have applied skim coat for smoothing many, many thousands of square feet of old rough plaster and drywall for paperhangers. It's not difficult really, but it is a job most of them would just rather offload and get on with what they prefer - hanging paper.

Here are some basic tips for how I approach smoothing rough walls (or ceilings)

(For my full step by step, professional system, see my Pro SKIM COAT GUIDE - it's downloadable.)

First, be sure the surface is reasonably clean. Usually I will ask the customer before I arrive to wipe down the walls with warm water and a sponge.

Second, if the walls have cracks, I clean them out, fill those that need it and then stick tape over all cracks with joint compound. In other words, treat each crack like I would a drywall seam. If this step is skipped, there is a very good chance that at least some of the cracks will reopen and show through your new wallpaper later.

Hot Mud?

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SIDEBAR: You don't have to use hot mud for taping or skim coat. I do to make things go faster. You can use regular all-purpose joint mud.

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Third, because I want to minimize my number of trips to the job, I will use hot mud to smooth out those rough walls. If I have any doubts about getting good adhesion, I will stir some plaster bonder into my water before mixing in the powder.

Fourth, I use all-purpose joint compound for the final smooth coat of mud. This is finer grained than the hot mud I use and is a lot easier to sand.

If all goes well, I can do my three coat system in one day. I then return a second day and sand out the tool marks, lines etc. before putting on two coats of drywall primer/sealer. (PVA primer)

Now the paperhanger will be happy!

Tips for the Applicator (you?)

What follows are some general ideas I recommend.

When I do skim coating, I like to use the plasterer’s hawk and trowel. This is a wonderful set of tools, but it take some practice to get proficient. For most folks, the eight or ten inch broad knife and long mud pan are easier to use.

Before you start mudding, it would be a good idea to put masking tape on all trim. The wide blue painters tape works best for this. Make your lines straight, and don’t overlap onto the walls or ceiling.

Now you can lay on the mud, using all-purpose joint compound as the easiest all around product to learn with. I would recommend you don't thin the material before you start, or very little. That will hold down the problem of material dripping off the bottom of your knife when doing horizontal strokes.

It helps to start at the top of the wall and work your way down. Don’t get the mud on too thick. It’s going to look rough your first time round, so don’t worry.

When your first skim coat is dry, you can knock off excess lines and chunks with your knife held pretty flat.

Your second coat will be devoted to filling in the rough places left in the first coat. If you are covering some fairly rough texture, you will find that even the second skim coat will not look so hot either. So a third coat is often required. Remember, you will be using sandpaper at the end, so utter perfection is not going to happen before that.

It may be that you are skim coating a wall that has multiple repairs you have done before.. The purpose then of your skim coat layers is to hide all remaining textured areas. So when you are done, you will have an entirely new surface, ready for primer and wallpaper or paint or maybe a new texture.

To get my complete step by step guide for a professional looking job, check out the skim coat guide here.

And, finally, don't forget to put on a couple of good coats of drywall primer/sealer (water-based PVA). This eliminates surface porosity and make the paperhanger's task much easier.

If at this point, you decide you would rather put on a new texture instead of wallpaper, here is a resource you may want to utilize. Wall Texturing Techniques

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If it's new drywall you want to get perfectly smooth, then you need to learn how to smooth coat drywall.

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