Dot and Dab – Is it Worth Doing?
When embarking on a new build or renovating a property, or just refinishing a single room, there are a lot of decisions to make, both in a fundamental sense and in an aesthetic one. One such decision is the way you want your walls to be finished. Do you want to have the room skimmed with wet plaster? Do you want to get a little extravagant and have something like Venetian Plaster installed? Or do you want to keep things simple and opt for dot and dab?
It’s a question many new build owners face, and the answer is typically a matter of economics. Most of the advantages of dot and dab are ones of a financial and time-saving nature. Whether dot and dab is worth it depends entirely on where your priorities hit the hardest. If your budget is the great decider in your decisions, dot and dab is undoubtedly cheaper than the alternatives. However, there are many issues with dot and dab that you don’t get with those alternatives, issues which we’ll take a closer look at shortly.
Ultimately there is no clear answer to whether dot and dab is better than the alternative since your circumstances will play such a large part in determining what “better” means in this context. But, while we can’t make a single sweeping verdict on dot and dab that will apply to everyone, we can certainly give you the information to make that verdict yourself.
What is Dot and Dab?
The typical structure of a building, such as a house, has an underlying building material whose purpose is to support the walls and floors of the property. In most cases, this material comes in the form of literal building blocks—bricks. This material is excellent at what it does, but it doesn’t necessarily make for the best finishing surface from an aesthetic point of view. Well, unless you are going for industrial chic. For most of us, it is necessary to cover that bare surface with something more visually appealing, and it is here where dot and dab comes in.
Dot and dab is the process of dabbing blobs of plasterboard adhesive onto the internal faces of the structure and then pressing the plasterboard into place, where the dots of adhesive will hold it and eventually set for secure, long-lasting hold.
Dot and dabbing has the advantage of being considerably quicker to install than something like wet plaster—which involves covering the entire surface with multiple layers of plaster—because there is significantly less plasterboard adhesive required, and no time spent smoothing going over everything to get a smooth surface.
Plasterboard often comes with a finished surface, meaning it is designed to be painted on. This means that the only finishing required is at the seams where two sections of plasterboard meet.
What are the Problems with Dot and Dab?
We’ve talked about how dot and dab is cheaper and less time-consuming to install, but what about the disadvantages? The primary disadvantage is the fact that dot and dab leaves a cavity behind the plasterboard. Unlike the intentional cavities left in the walls of a building, which are often filled with insulation and designed to prevent moisture build-up, the cavity behind a dot and dab-adhered plasterboard is a free passage for airflow.
This can create drafts in strange places, such as from under the skirting board and around light switches and plug sockets. Unfortunately, if air can get behind your wall, so can moisture, and that is the main problem dot and dab can cause. If moisture can get behind your wall, it can become a breeding ground for damp, mould, and algae.
Damp can cause problems with your plasterboard becoming soft, as well as developing unsightly stains. As for mould and algae, the best-case scenario would be your home develops unwanted odours from behind the walls. However, in more severe circumstances, it can become a health risk as mould spores get into the air you are breathing.
The final major disadvantage of dot and dabbing is one of strength. Plasterboard is relatively easily broken, especially when compared to a solid wall with a wet plaster finish. Now, the gap behind a piece of plasterboard that has been fixed in place by dot and dabbing should not be that large, but there will likely be enough space that an impact could dent or crack the plasterboard. If a particularly thin size of plasterboard is used, this could be done as easily as leaning your hand on a weak spot to steady yourself as you remove your shoes!
Can you Dot and Dab Over Existing Plaster?
Dot and dabbing over existing plaster is a very bad idea, and dot and dabbing over plasterboard that is held in place by a previous dot and dabbing venture is even worse.
The moisture in your plasterboard adhesive can soften the plaster and plasterboard, resulting in a significantly weakened hold at best, and your whole finish ending up in a heap on the floor at worst. If you absolutely must refinish your walls with plasterboard, unfortunately, you would be looking at gutting the existing plaster first. Alternatively, you could frame the walls. Fixing a wooden framework to the old wall with secure screws and then fixing the plasterboard to the wood with plasterboard screws. However, this will take a chunk of internal volume out of your room.
Should you PVA a Wall Before Dot and Dab?
If the surface you are dot and dabbing onto is bare—which is to say it has never been treated or painted, or is still the construction material exposed—you will want to give it a treatment of PVA before you dot and dab onto it.
This is because the bare, untreated surface of something like stone, brick, or cement is porous, and will draw the water out of your adhesive. Another reason is that it will likely be coated in a fine layer of particles that will come away easily. The problem with this is that if you apply an adhesive to this layer of particles, the adhesive will stick to those particles rather than the surface you are dabbing onto, significantly reducing the adhesion.
By applying a coat or two of PVA mixed with water, you “seal” the exposed surface, preventing it from losing surface particles or absorbing the water in your adhesive.
Can you Dot and Dab an Uneven Wall?
You can undoubtedly dot and dab onto uneven walls. In fact, it is easier to do this than it is to apply wet plaster. Of course, there is a question of how uneven your walls are. If you are attempting to dot and dab onto comically uneven walls, it will not be possible to get the desired amount of strength out of your dots of plaster adhesive. It will also create larger spaces behind the plasterboard in some areas, which will both make the plasterboard less resistant to damage, and create more space for air to get behind the walls.
For slightly uneven walls, however, such as a bare-brick surface where the bricks are not straight-cut, dot and dabbing will allow you to relatively easily achieve a smooth finish in considerably less time than it would take to apply a scratch render and wet plaster the whole surface.
Can you Dot and Dab onto Brick?
Not only can you dot and dab onto brick, but this is also one of the most common situations where dot and dabbing is used since brick is one of the most common construction materials used to build with. It also allows you to get a smooth, flat surface relatively easily without having to worry about applying lots of scratch render and wet plaster, which would take much longer.
As noted above, you will want to treat the bare surface of the bricks with PVA before attempting to dot and dab onto it.
Can you Dot and Dab onto Wood?
You cannot dot and dab onto wood due to the porous and absorbent nature of wood. The plasterboard adhesive would have a weak hold at best, assuming it held at all.
Fortunately, this does not mean you cannot use plasterboard on a wooden surface. As touched on above, you can frame the area out with more wood and then fix the plasterboard to that. Or, if the area in question is already a framework, you may be able to fix the plasterboard directly to it. Naturally, you will need to make sure that the surface you are fixing the plasterboard to is straight. Unlike dot and dab, which is very forgiving of the uneven-ness of the underlying surface, screwing the plasterboard in place means that it would be forced to conform to whatever that underlying shape is.
Dot and dab has many advantages from a time and monetary perspective, but it also has many disadvantages in the long run. While we appreciate that money is often a pressing factor, the finish on your walls is not a short term thing, and removing dot and dabbed plasterboard is no small task, so it would certainly be worth thinking long and hard about whether the cost savings are worth it.