Plastering Advice please

20400keith

I'm having a new kitchen built.

Builder is suggesting plastering over plasterboard on the walls, rather than sand and cement. He says sand and cement will take too long to dry out this time of year.

Any thoughts which is best - plasterboard or sand and cement?

Thanks.

wallbash

Two of my walls are plasterboard, two are sand/cement/ plaster

Not found any difference

gerryscot

Sorry cant answer your question, however i made a complete fool of myself when i got walls plastered, I came home to horrible brown walls and said to the guy you never asked me what colour of plaster i wanted, not thinking the plaster changed colour when it dried.
:rotfl::rotfl::rotfl:

I felt like a complete Idiot!!!

missindecisive

a thin skim of plaster over plasterboard will dry much quicker than a render mix

tlrtone

plastering over plasterboard is the modern way of doing things.
Often called "Dot and "Dab", they put a plasterboard adhesive up in dabs and press the board onto it.
Just had my extension done in the same way, dried out in 3 days and painted it and moved in within a week!

jimbugalee

I think your builder may be correct if you already have plasterboard but any outside walls should be rendered up to waist height (thereabouts) and then plastered on top. This helps prevent damp V important in the future if you plan to sell as we've just had to have all of the damp removed from downstairs because it wasn't plastered correctly.

House_Hunter

I've always lived in old houses with solid (ish...cob??) walls, so prefer a proper render mix as opposed to plasterboards...

For some reason, I always feel more confident attachign things onto a render mix plaster as opposed to plasterboard as well.....not sure if there is any real difference though..

David_Aldred

Hi - if you opt for plasterboard on dot and dabs don't use standard grade dry wall adhesive as it is highly hygroscopic and you run the risk of seeing circles of damp upn the plasterboard / decoration. Foil backed boards are preferred and where applicable moisture resistant / fire or sound blocking boards should be used ensuring the boards do not make contact with the floor. Not a complete list buy hope this helps, Kindest regards David Aldred Independent damp and timber surveyor

dampdaveski

Keith,
If it's a new build kitchen extension, as in it's all new construction (ie you are not going to be plastering onto any existing old brick walls). Then normal plasterboard (preferably 12.5mm) and normal dry wall adhesive is perfectly acceptable.
that is the application the dot and dab method is designed to be used in, virtually every new house built has this type of plastering used. I used it when I plastered out my own extension.
You should not use dot and dab on old brickwork ( a loose guide is anything over 30 years old).
If the extension floor is solid it is good practice to keep the boards app 25mm (inc adhesive) off the floor, a roofing lat laid along the wall is a good way to do this.
If it's a wooden floor or a floating floor then I suggest that you DO place the boards at floor level,(ie no gap) this will help with draught proofing. just make sure the plastic DPC is not bridged or it could cause problems in the future
hope this helps
DD

David_Aldred

Hi - I agree with Dampdave in so much as out of preferance standard grade plasterboard without any barrier to dampness is not a good choice for properties with a history of dampenss or salt contamination. The British Gypsum White Book and websites will give appropriate alternatives for where you wish to use a board in a damp environment and you do need to be mindful of letting warm moist air get behind the system where it may condense out on colder surfaces.

Accordingly the provision of fully effective vapour control layers on the warm side of things is a mandatory requirement. I know Dave considers sitting the boards directly upon a suspended timber floor may be appropriate in some situations but the floor will move seperately to the plasterboard wall and if the relative humidity of the sub floor void is high then there will be a tendency for this moisture laden air to migrate up behind any plasterboard so if you do opt to do this please ensure effective vapour control.

To walls and chimney breast areas which are prone to dampness and salt contamination the use of a polyethylene studded membranes with effective vapour control layers prior to plasterboarding with a moisture resistant foil backed board which may include insulation to cold walls such as Kingspan Kooltherm may be considered with appropriate external ventilation where necessary on the cold side of the system.

Polytheylene studded membranes can be bought direct from the manufacturer / supplier if you cannot source them from your local builders merchant. Developed initially for basements they are useful above ground level too where traditional re-plastering may be prone to premature failure due to dampness, contaminates and poor substrates. Trade-names include Oldroyd, Delta, Platon and Newton. For further details please look under the phrase of cavity drainage membranes on the following websites and one of their area reps will usually be pleased to visit site to show how to apply the product successfully though I would strongly recommend this allways be done to full room height to avoid any issues at the interface. The product is easy to apply and relatively cheap.

One of the issues of traditional re-plastering to damp salt contaminated walls is it requires a very standard of surface preperation and application if it is to be succesful. It introduces consierable moisture into the property when the aim is to dry the property down not make it wetter, and the client as a layperson has no idea if that plasterer has undertaken their work correctly when they want paying whilst the wall is still damp. If the area fails to dry down or degrades they tend to blame anyone and everything but themselves.

The membrane system introduces far less water, is able to be decorated far sooner, gives the client confidence in that they can see a physical barrier being applied and it has to be said rather deviously that barrier will without opening the area up, prevent any surveyor in the future from metering the wall so they will not often detect dampness as it tends to cover up a multitude of sins including issues of penetrating damp that may be difficult / cost prohibitive to resolve and any suspicion of rising dampness. Be mindful hwever that when appied to walls only the system will not hold back any liquid moisture which would if it occurred simply trickle out the bottom alerting the client that there was a major leak or interstital condensation issue that needed to be resolved without delay.

See:

Safeguard Chemicals - Redkiln Close , Redkiln Way, Horsham, Sussex, RH13 5QL (tel 01403 210204) www.safeguardeurope.com

Wykamol Group – Unit 3, Boran Court, Network 65 Business Park, Hapton, Burnley, Lancashire BB11 5TH (tel 0845 4006666)
www.wykamol.com

Sovereign Chemicals – Park Road, Barrow-In-Furness, Cumbria. LA14 4QU ( tel 01229 870800 )
www.sovereignchemicals.com

Hope this helps kindest regards, David Aldred Independent damp and timber surveyor.

swiftandsure

20400keith wrote: »

I'm having a new kitchen built.

Builder is suggesting plastering over plasterboard on the walls, rather than sand and cement. He says sand and cement will take too long to dry out this time of year.

Any thoughts which is best - plasterboard or sand and cement?

Thanks.

Whatever you go for this is just nonsense. It is inside the house and will be dry enough to skim within a couple of days. Personally I would always go sand and cement rather than plasterboard. I want stuff I can drill or hammer if I wanted to, plus it will last a lot longer than you or I will.

Sounds like he just wants an easy time of it.