Levelling a wall...

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Have you ever noticed some walls in the house (especially kitchen) where cupboards are leaning inwards or outwards?  Perhaps a stair-wall that looks as though it is falling in? or maybe even a chimney breast that looks a little 'wonky'?

This tutorial will teach you how to get the wall 'plumb' that's level to you and me ;)

Firstly one must ascertain how much 'out of level' the wall is, an easy way is to grab a piece of timber (say 3x2 inch by 3 inch long) and place it at the top of the wall, then dangle a piece of string with a weight attached, knowing the width of the timber the string is dangling from gives you a measurement at the bottom of the wall i.e. If the timber is 3 inch at the top then the gap between the string and the wall should be 3 inch also.  One thing I can guarantee you is that the measurement WILL be different!  Most walls are (almost plumb) and once plastered (should) be plumb BUT they seldom are!

'Why would I want my walls to be plumb (level) in the first place?'

Good question! Let's say that you are going to fit some flat mirrors to a wall, once fitted the reflection from the mirrors will show door casings or tall lamps etc  To look at a reflection and see a lamp that looks as though it is falling inwards or outwards makes you think that the mirror or lamp is not quite straight or level and can cause havoc once noticed! What about some kitchen cabinets that don't line up with the door frame? or that overhead pan holder that dangles above the Island that makes the cupboards look all out of level..

There are lots more examples that I could draw upon but I think you get the idea.  So how do we level them up?

There are 2 main ways to level a wall;

a) Dot 9.5mm plasterboards on using plasterboard adhesive
b) Plaster some Bonding coat on and rule it level prior to skimming it.

In order to dot plaster-boards on you need to take into account the skirting board (if any) and/or door casings/architraves etc  If the boards when dotted come level with the architrave then you will have to fasten timber batons to the frame in order to bring out the required depth first prior to fitting the architrave or rip out the casing completely and replace with a wider one.  The depth of a board (9.5mm) coupled with the dabs of adhesive (5 - 10mm) brings the wall out to around 15 - 20mm then there is the plaster at around 3-5mm, as you can see the final thickness is quite deep.  On the other hand you can 'wet plaster' the wall using a sticky backing coat called 'bonding coat' (its in a purple bag) and gain a far better control over the final thickness.
Plastering using the bonding coat method is not as hard as one might think, first of all we need to know how far 'out of plumb' the wall is so that we can apply the proper thickness in order to bring it back to level, to do this we simply measure the top and the bottom, if the bottom is 'more' than the top, we have to apply more plaster at the bottom and less at the top, if the measurement is less we need more at the top than at the bottom.

Screeds...we build a wall out level using screeds, these being around 5-6 inches wide and the entire length of the wall from bottom to top, because the wall is out of level we would see more plaster thickness at the bottom (or top depending) and less at the top if viewed from the side.  

How do you put screeds in place?

Simplicity itself;  Mix some bonding coat to a consistency akin to 'angel delight' or thick yogurt and using a plastering trowel apply a bed of bonding coat to the wall in a vertical direction working from the bottom to the top, then we 'rule' this off using a straight piece of timber (wet it first) until it is flat, then pop the spirit level on and check it, if it needs more at the top or bottom then simply add it until the desired thickness/level is reached.  Apply enough screeds to the wall so you can rule 'between them', once they are all applied allow to set.  Making the wall level from here on in is easy, just mix and fill in the spaces between the screeds making sure to keep it level with the screeds, once finished allow to set in order for it to be skimmed.
Dotting and dabbing is easier by comparison but you have to consider the disadvantage (thickness!) remember that once dotted and plastered a 9.5mm plaster-boarded wall would be some 23mm thick! That is at it's absolute thinnest!! With dotting plaster-boards you simply mix the adhesive to the same consistency as bonding coat and apply 'dots' of adhesive to the wall at roughly 350mm centre's or (14 inch) then place ALL the boards to be levelled onto the dots and gently tapped into place using a long thick piece of timber, tap them horizontally, vertically and diagonally in order to get them all in-line then put your level on and either tap them in at the top or bottom in order to attain the required level.

If in a kitchen, try to find out where the units are to be fixed and place solid dots at these locations, this will facilitate at much stronger fixing and give the cabinets a chance of staying put!  Try to apply solid dots along the skirting line too and around switch boxes, in other words anywhere there may be something fixed or get constant traffic.

*solid dot* is a line of adhesive akin to a screed as opposed to a singular dot.

The benefits of dotting walls are; Easier for the average DIY'er, faster as they don't necessarily need plastering (some joint tape and a bit of compound will do) and added thermal value to your home (they leave a space between the wall and the back of the board, creating a breathing space).
Bonding coat however does require a little more skill to get right and is not as high on thermal value than boards but gives a complete solid bond to the wall i.e. fix anything anywhere.

Dave
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