Advice on skimming

[123abc]

I would like to re-skim this internal wall on a 1930’s semi. It looks like the half of it’s been rendered with lime and half of it with cement. Can I just PVA and skim with multi finish? Or need to do something else first?
And second question: Part of the plaster on the sealing has fallen off and exposed the plaster boards. I think they are the original old plasterboards. What’s the best way to patch them up?
Thanks in advance and please be gentle with me if I sound silly  I’m just a newbie.

 

[HERTS P&D]

Hi, I can't answer question 1 but I can help with question 2.

If plaster has fallen from the ceiling, then what that normally means is the plasterboard is 'loose'. This can be fixed by refixing the ceiling with longer screws and banging in any nail heads you see. Then having it plastered.

But what I did in my home was to re-board the ceiling with new plasterboard and have the ceiling plastered. Looks loverly.

Andy

 

[2929twin]

PVA to the rescue.
1 As long as there is no loose areas should be ok for 2 coat skim. If the stronger sand cement section is to lower part its prob part of a damp proofing operation and more recently applied.
2 Unlikely 1930 used board, probably had lath and plaster then, i guess its been changed, check for loose `feeling` in board lots of DIYers are scared to put fixings in every 8 inch. so boards move and then...

 

[123abc]

Disaster!!!
I did PVA the wall (5:1) yesterday and twice today (3:1). Still the plaster started cracking after only 15 min on the wall. I used B&Q branded PVA and Multi Finish, the wall is done with Thermalite blocks. What did I do wrong???

 

[external]

you forgot the backing plaster

 

[roughcaster]

Disaster!!!
I did PVA the wall (5:1) yesterday and twice today (3:1). Still the plaster started cracking after only 15 min on the wall.

I used B&Q branded PVA and Multi Finish, the wall is done with Thermalite blocks. What did I do wrong???

I'm with External here, and am assuming that you've put the multi finish straight onto the pva'd thermalite block, without a float coat of some type???

 

[123abc]

I asked:

I would like to re-skim this internal wall on a 1930’s semi. It looks like the half of it’s been rendered with lime and half of it with cement. Can I just PVA and skim with multi finish? Or need to do something else first?
And was advised by 2929twin

PVA to the rescue.
1 As long as there is no loose areas should be ok for 2 coat skim. If the stronger sand cement section is to lower part its prob part of a damp proofing operation and more recently applied.
Now I see that you can't trust everyone on this forum
I've learn the lesson.
So gents, please give me more details about the backing plaster. And after how long I can apply the Multi finish? Thanks.

 

[Alastairreid]

i would have given the wall a tight coat of bonding or hardwall basecoat, wait an hour or 2 then a couple of coats of multi.
sounds as though you havent sealed it well enough to control the suction.
the advice you got earlier from 2929twin was valid!
as long as the existing substrate is solid ,level with no deep voids to fill,
the method explained earlier should have worked with no problems.

 

[Micilin]

i would have given the wall a tight coat of bonding or hardwall basecoat, wait an hour or 2 then a couple of coats of multi.
sounds as though you havent sealed it well enough to control the suction.
the advice you got earlier from 2929twin was valid!
as long as the existing substrate is solid ,level with no deep voids to fill,
the method explained earlier should have worked with no problems.

Same here.

 

[Richard C]

i would have given the wall a tight coat of bonding or hardwall basecoat, wait an hour or 2 then a couple of coats of multi.
sounds as though you havent sealed it well enough to control the suction.
the advice you got earlier from 2929twin was valid!
as long as the existing substrate is solid ,level with no deep voids to fill,
the method explained earlier should have worked with no problems.

I also agree.

I would like to re-skim this internal wall on a 1930’s semi. It looks like the half of it’s been rendered with lime and half of it with cement. Can I just PVA and skim with multi finish? Or need to do something else first?

Where in this, your original post, do you make it cleat its back to block? No one in their right mind would advise you to skim straight over blocks with finishing plaster & that should be obvious even from reading the basic instructions on the bag!

Now I see that you can't trust everyone on this forum
I've learn the lesson.

The fault is entirely yours my friend for not making your post clear & the slagging is completely unjustified. I think you owe 2929twin an apology & the rest of the spreads on here for that matter.

 

[123abc]

With all the respect to you Professionals lets clarify few things.
In my first post I clearly said that the wall has been rendered, half of it with cement and the other half with lime. You have to understand that people who ask questions on this forum have either very little or no knowledge at all on the subject. So when you give us an advice (instructions) it has to be step by step and with all the details.
My question was: Can I just PVA and skim with multi finish? Or need to do something else first?
The answer was: PVA to the rescue. As long as there is no loose areas should be ok for 2 coat skim.
I asked the question because after reading the old posts I wasn’t sure what to do. I did us instructed and instead 2 coats with PVA (as usually recommended on this forum) I did 3 of them. There was nothing in his advice about some backing or bonding coat.
However I can accept that I wasn’t clear in my second post. I wanted to give more information but didn’t explain that the Thermalite has been rendered as above. So, my apologies for the second post. But if 2929twin thought that there were not enough information in my first post he should have said so instead of jumping in giving an advice. I’m sure that 2929twin gave the advice with all the good intention but my point was: This is DIY Forum, and most of the people haven’t got a clue about the stuff you do every day. So have that in mind next time when you advice someone and give as much details as you can. Thanks to all that gave me more details about my problem.

 

[Richard C]

So it’s not back to block then, more confusion! None of the regular contributors on this forum would intentionally give you wrong information &, as far as I can see, none have in this case. The advice you were first given is still broadly correct but something has gone wrong with your preparation that has failed to control the suction. The advice you were given was not at fault, the problems you've had are due to a lack of understanding, experience & preparation on your part. It always pays to research something your going to “have a go at” by doing as much research as you possibly can & a good place to start is the forum archive threads. Plastering cannot be compared to other simple DIY tasks, it’s not like painting or wallpapering & something you can “pick up” after asking a simple question about PVA & a trip to B&Q on a Sunday afternoon to buy a couple of bags of Multi, some PVA a trowel & bucket.

 

[1john]

the advice is correct, i am afraid that you have done something wrong. people can only give advice on the info you provide. I cannot see the need to give full on step by step instructions. Read the forum, learn about what you are about to be doing (as someone who can do a few trades, yoou have chosen one of the most difficult to pick up) once you have a good understanding of what you are doing, then you should ask questions on parts that you dont understand.

A complete step by step guide would end up like the bible if all variables and scenarios are taken into account. I dont think any of the spreads here are going to type all that up, certainly not in their own time, for no financial reward and out of the kindness of their heart.

Now back to business, if the wall is flat enough for you and the disasterous skim coat is stuck firm and not blown anywhere then you can leave it dry, pva it the night before you plan on skiming it again and pva it before you start, making sure it is tacky when you apply your first coat.

Make sure your tools and buckets are clean, very clean, make sure your water is cold clean and fresh and good luck. there are so muny things that effect plaster drying times, two that you can control yourself within reason are suction with pva and the cleanliness of all of your tools and equipment.