Preparing Ceiling - cracks in plasterboard

[SproutsDad]

Hi, my bedroom ceiling in 1930's house probably still has old ceilingite under vinyl silk, but holds sound, no peeling. The ceiling surface is shiny(silk) and generally flat and defect free, slopes down last 40cm at eaves.

I want to bring surface up to good standard and roller matt white onto it. BUT the plasterboard joints are mostly visible by cracks and filler coming away. Possibly never taped originally?

Can I rake out and fill those joints with something flexible but good adhesion that will sand/dress downand leave minimal traces of the join when finished? And stay there? It would be a pity and lot of ££ , grief and time to replaster just for that. Your kind advice please !!

 

[Zampa]

I dont know what ceilingite is im sorry bit as for raking out cracks etc..its normally the right thing to do, but if theres skrim tape on the joints and you slice through it you'll be in even more trouble with the joints.

Joints like that on ceilings are hard to deal with becasue of expansion and contraction of roofs etc..You might want to think about raking them carefully, filling, taping over the filler and then feathering the sides of the tape with filler, then lining the ceiling with 1000 grade lining paper. (after giving it a thinned coat of dulux stain block or completely rubbing down the silk and removing the sheen...use ready mixed paste too)

 

[SproutsDad]

Thanks for the reply & advice. I understood that this wasn't going to be an easy one. Have papered a ceiling before in same house, 800 grade I think. With lots of prep the result was great, but a few years on some areas show slightly creased paper at the board joints. ,
Have read other topics and that some plasterers want to re-board before skimming, mine has sloping ends at eaves so could be lots of £££.

I'm sure/hope it can be done without replastering as the main surfaces are very flat and clean, it's just the joints that are ugly. I am prepared to paper it if you feel that will be the best, but the prep has to be done anyway

Celingite (trade name I think) was the old chalky, powdery paint that usually washed off or reacted with modern vinyl paints.

A few answers to your approach please.....
1. What is the tape you refer to? What adhesive do I use for it?
2. What filler do you mean? Some smooth flexi fillers can't be sanded, others are a bit gritty.
3. Do you mean to use the Dulux stain block instead of or as well as sanding the old vinyl, it is very hard to rough up, almost glazed.
4.

Might sound crazy but how about this? Please say if no good/bodge!!
1. Brush a PVA wash in raked out joints.
2. Push a grab adhesive NoNails etc well into gaps/joints, leave just below surface.
3. Use soft flexi filler & sand level.
4. I can see many of the joints above in the loft, those at 90deg to joists. I could bed battens in grab adhesive to support them, minimise movement.
4. There is a Polycell 'Crack-Free-Ceilings' matt white flexible paint compound, 5L £20. Is supposed to bridge small cracks and flex with a moving ceiling surface.

Thanks for your help, I can post photos if it helps?

Sprout is the 3-legged cat!!

 

[Richard C]

Read this topic before you decide what to do;

//www.diynot.com/forums/viewtopic.php?t=107344

There are several other similar threads.

 

[SproutsDad]

Thanks Richard,
I have read the topic and many others that you and roughcaster have advised on. The soundest advice seems to be to tackle the problem at source - the plasterboard joint flexing. But it seems that even that could result in cracking………. All very frustrating!

I have seen some of your in-depth replies to other queries, you clearly do this a lot and I would appreciate your feedback on this as much as possible.
I can minimise the movement of boards by screwing to joists above at the joints.
I would think the process is like this………..
1) Secure the board joints as good as possible. What type of 1.5" screws, normal c'sunk?
2) Is there then benefit in supporting the exposed joints from above - grab adhesive batten pieces to the loft side of the board joint between joists.
3) Tape up joints - what tape? I have found 'wall repair & crack cover tape' - 50m x 10M £2.79. Is this the type, it is self adhesive? Or a jute or fibre tape and adhesive, which one? http://www.tapes-direct.co.uk/index.php?main_page=product_info&cPath=132&products_id=937
>>> Can the old paint & skim be cut back to the board surface along the joint (gains 3mm), even routered back(!!) so that it can be taped and then filled with a minimum of reskimming & tapering out? This would be rather like they do with tapered board on drylining.
4) Fill over tape & taper out with skim plaster, would ready mix skim be ok? Wickes do an easy to use large tub.
5) Do I then need to line it with 1000 grade?
6) Paint matt white
AND …….IF THAT FAILS CALL A PLASTERER?.
Or do I cut to the chase and do that anyway?
So how much for a plasterer to tape & skim the lot? I know you can't quote £'s is this a day & half labour + materials for taping & reskimming a ceiling 11sq metres, with angled eaves?
Look forward to your reply, much appreciated.
Many thanks.

 

[Richard C]

1) Secure the board joints as good as possible. What type of 1.5" screws, normal c'sunk?

Use only csk. drywall screws; I get mine from Wickes

2) Is there then benefit in supporting the exposed joints from above - grab adhesive batten pieces to the loft side of the board joint between joists.

If the crack runs with the joist, just add screws either side of the crack around every 250-250mm; stagger them & watch you don’t hit the existing nails. Cracks on unsupported edges that run across the joists would certainly benefit from support above if you can get access.

3) Tape up joints - what tape? I have found 'wall repair & crack cover tape' - 50m x 10M £2.79. Is this the type, it is self adhesive? Or a jute or fibre tape and adhesive, which one? http://www.tapes-direct.co.uk/index.php?main_page=product_info&cPath=132&products_id=937
>>> Can the old paint & skim be cut back to the board surface along the joint (gains 3mm), even routered back(!!) so that it can be taped and then filled with a minimum of reskimming & tapering out? This would be rather like they do with tapered board on drylining.

My method uses Multi Finish plaster but I suppose you could use Easy Fill; dig the cracks out well along their entire length with one of those 3 corner scraper thingies; no need to cut back or remove the paint or plaster if it’s sound but score the paint well if it’s Vinyl to provide good key. PVA fill the crack & surrounding ceiling & fill flush with a little Multi-finish. Apply 3 overlapping lengths of glass fibre reinforcing tape over the crack. Mix up a quantity of Multi finish & PVA the whole lot again; when tacky force an initial skim of plaster well into the tape mesh. Mix up some more Multi Finish & just as the first skim over the tape starts to firm, skim the whole length of the tape blending out into the ceiling around 200-300mm either side & when it’s ready, trowel up the whole area working the edges hard to give a seamless blend between old & new; don’t worry about the difference in ceiling height, if done properly no one will ever notice it. There may be one or two little bits that need filling but don’t worry about that yet.

4) Fill over tape & taper out with skim plaster, would ready mix skim be ok? Wickes do an easy to use large tub.

I won’t use filler & use Multi Finish as above for the lot; if your not using plaster then I suppose you could use Easy Fill as above but I’ve never don it like that so can’t comment on it’s likely success.

5) Do I then need to line it with 1000 grade?

Line it, why? If it’s done properly it’ll look as good as new.

6) Paint matt white

Mist coat the area when dry & fill any imperfections that may be visible; I will occasionally get the odd bit at the edges but not much. Paint whole cieling in the normal way.

AND …….IF THAT FAILS CALL A PLASTERER?.
Or do I cut to the chase and do that anyway?

Maybe the best bet if you’re not confident but you must get someone who knows what they are doing or the cracks will reappear in a very short time. I have almost 100% success rate with this method but nothing is guaranteed!

So how much for a plasterer to tape & skim the lot? I know you can't quote £'s is this a day & half labour + materials for taping & reskimming a ceiling 11sq metres, with angled eaves?

Prepping & skimming a 11 sq/m ceiling will take less than ½ day but expect to pay for it; plastering rates vary depending on location & availability but expect anything from £160 - £200/day & it’s only a one man job; materials cost next to nothing, less than a tenner.

A repair should cost less & should only take a couple of hours, it’s a question of finding someone prepared to do it; many will prefer to do the whole ceiling as they can potentially charge for the whole day although, as I said, it shouldn’t take that long!

 

[SproutsDad]

Thanks Richard, ... that's what I call a thorough reply, really grateful for all that detail.
I have skimmed a wall successfully before so with your detailed guidelines I feel confident that I can make a 'silk purse' out of this.

Can you clarify a few points please? Some names you use are not familiar ones....

1) Multifinish = ? Is this a skim plaster, Thistle topcoat etc? Can I go to a builders merchant and get it or even Wickes - ? A brand name please?

2) Easyfill = ? is this the ready mixed skim coat that I refer to? There is a Wickes one that goes on like butter and is very easy to finish.

3) Tape = glass fibre reinforcing tape, width about 60mm I would think? Again should this be a particular brand? Wickes & Screwfix have plater jointing tape but no specific mention of glass fibre reinforcing.

The Wickes ones are
a) Plasterboard Jointing and Repair Tape - glass fibre self adhesive 48mm wide. http://www.wickes.co.uk/Plaster-Tap...terboard-Jointing-and-Repair-Tape/invt/163566

b) Plasterboard Tape 48mm wide - self-adhesive fibreglass mesh tape. http://www.wickes.co.uk/Plaster-Tapes-Accs+Adhesives/Plasterboard-Tape/invt/163685

Same comment against both of these tapes is --- "for covering drywall joints prior to texturing and finishing. Requires no pre-plastering, which also reduces drying time".

>> If I use a self adhesive tape, how do I modify your method, or do I bed it in plaster as you describe anyway?

4) By how much will this method raise the ceiling level at the peak of the joint? ........ 3mm or there abouts feathering out to 0mm over 200 to 300mm I would think??

5) Is it the PVA, plaster and glass fibre tape that form the firm bond?

6) And finally my float/trowel has been used for plaster and screed so I'm due a new one. Will £15 to £20 do the job - size 14" or 11"? Screwfix have a number, stainless, carbon steel etc.


I'm really thankful to you for all your help.
All the best

 

[Richard C]

Can you clarify a few points please? Some names you use are not familiar ones....

1) Multifinish = ? Is this a skim plaster, Thistle topcoat etc? Can I go to a builders merchant and get it or even Wickes - ? A brand name please?

Yes all BM’s sell it but, believe it or not, B&Q is about the cheapest place I’ve found, they store it well & sell so much of it it’s always fresh as well.

This site is very useful, I use nothing but their products.

http://www.british-gypsum.com/products/thistle_plaster_products.aspx

2) Easyfill = ? is this the ready mixed skim coat that I refer to? There is a Wickes one that goes on like butter and is very easy to finish.

Could be, see the web site; it’s an easy to sand joint filler used on taper edge boards which are not going to be plastered. Personally I don’t use it as I always go with a plaster finish. I never use one coat plasters either, I hate them but I will agree they have their uses for DIY.

3) Tape = glass fibre reinforcing tape, width about 60mm I would think? Again should this be a particular brand? Wickes & Screwfix have plater jointing tape but no specific mention of glass fibre reinforcing.

The Wickes ones are
a) Plasterboard Jointing and Repair Tape - glass fibre self adhesive 48mm wide. http://www.wickes.co.uk/Plaster-Tap...terboard-Jointing-and-Repair-Tape/invt/163566

b) Plasterboard Tape 48mm wide - self-adhesive fibreglass mesh tape. http://www.wickes.co.uk/Plaster-Tapes-Accs+Adhesives/Plasterboard-Tape/invt/163685

Same comment against both of these tapes is --- "for covering drywall joints prior to texturing and finishing. Requires no pre-plastering, which also reduces drying time".

>> If I use a self adhesive tape, how do I modify your method, or do I bed it in plaster as you describe anyway?

I always use self adhesive, glass fibre reinforcing & repair tape; brand doesn’t really matter.

4) By how much will this method raise the ceiling level at the peak of the joint? ........ 3mm or there abouts feathering out to 0mm over 200 to 300mm I would think??

It will raise the centre of the repair obviously by around 3mm but the idea is to blend this out around 200-300mm either side of the repair & if it’s done well, it’s surprisingly difficult for most folks to spot it especially if you blend it all out even wider where the wall meets the ceiling.

5) Is it the PVA, plaster and glass fibre tape that form the firm bond?

PVA acts as a seal & a bonding agent; the glass fibre tape provide the reinforcement & strength but it’s important you use additional screws either side of the joint as the flexibility & cracking is usually caused by the original nails not holding the boards sufficiently rigid against the joist.

6) And finally my float/trowel has been used for plaster and screed so I'm due a new one. Will £15 to £20 do the job - size 14" or 11"? Screwfix have a number, stainless, carbon steel etc.

Unless you plan to do a lot more plastering, a reasonable budget towel, though not ideal to polish with, will be adequate. My trowel started life as a budget offering but nearly 5 years ago, I didn’t know at the time I was going to get so involved with plastering & I’m tempted to get a “decent” one. But its’ well worn in, is perfect for me & gives a perfect finish so I’m loathe to change it.