Sealing where a velux meets the plasterboard to stop draughts?

thekooman

hi all,
Have noticed the last while that there is a draught coming in around the velux windows in the house where the plasterboard meets the velux.
what would be the best to maybe running around the edges to stop this from happening? would it be white silicon or maybe painters chalk?

anyone ideas or experiences of this would be great.
have attached images to show.

antiskeptic

thekooman wrote: »

hi all,
Have noticed the last while that there is a draught coming in around the velux windows in the house where the plasterboard meets the velux.
what would be the best to maybe running around the edges to stop this from happening? would it be white silicon or maybe painters chalk?

anyone ideas or experiences of this would be great.
have attached images to show.

tec7 is the way to go. It sticks like nothing else and stay stuck (I'd put a generous bead on and smooth with a finger). Expensive at about 13 euro a cartridge but has the advantage of a screw-on-cap and good storage life when part used - you'll end up using it for all sorts once you get hooked to it's versatility.

There are cheaper copies around - I see evostick doing something similar of late.

Be careful to by tec7 itself and not one of the myriad of other products made by the same company and packaged almost identically.

brendankelly

Iy should be illegal for these people to call themselves plasterers

AckwelFoley

brendankelly wrote: »

Iy should be illegal for these people to call themselves plasterers

I wouldnt blame the plasterers at all.

The cracking is from expansion in the timber structure.

From what i see, it looks like the slab isnt covering over the frame of the window enough

Tec 7 is a flex sealant and adh, applied correctly it should slove the problem

thekooman

cheers folks for the advice. just seen an ad on the telly there for TEC7... looks very "JML"! ill give it a go and will let you know how it looks.

paddy147

thekooman wrote: »

cheers folks for the advice. just seen an ad on the telly there for TEC7... looks very "JML"! ill give it a go and will let you know how it looks.

Its nothing like that JML SHYTE.:rolleyes:

Tech 7 works,thats the difference.:)

Ive used it on my 500 litre aquariam for fixing dead wood and bog oak to slate rock,to keep them sunk and on the bottom of the tank.

It works underwater 100% and does the job perfectly.:D

brendankelly

The plastering is like as if it was done with a yard brush.

You are correct . The plaster board is not fitted properly into the grove on the Velux. Other than that it is the plaster work that is at fault. There is a hole that flies or even a small mouse can get in and out. It is a cheap one coat plastering job and the person that did it should fix it and the architect that signed off on it should pay for the annoyance caused to the home owner.

scwazrh

brendankelly wrote: »

The plaster board is not fitted properly into the grove on the Velux. Other than that it is the plaster work that is at fault. There is a hole that flies or even a small mouse can get in and out. It is a cheap one coat plastering job and the person that did it should fix it and the architect that signed off on it should pay for the annoyance caused to the home owner.

You are dead right!There is grooves in all velux window frames that the plasterboard must slide into.Normally you need to shave the back of the slab to get it to fit.


For the OP,scrape back along the edges that hit the velux with a Stanley knife and then fill with flexible caulk .Tec 7 is great but is very expensive.Keep in mind though that you will need to reseal it every few years..

gsxr1

The groves in the velux are not ment to make the system draft free. . Its simply to locate the plaster board neatly.

It is also hardly a plasterers fault that the plaster breaks down and cracks in a new build.

I cant believe experienced people would make crazy comments like it should be illegal . :rolleyes:


Simply reseal when redecorating to cure the problem. No need for the drama.

Im not sure tec 7 would be ideal as it may not take paint so well. A tube of chalk seems like a better choice to me. Ask a painter for advise on the exact stuff for such an application



There are airtight ways to fit a velux but they are few and far between TBH. mosy are installed by roofers , and finished below by tackers and plasterers . Unless they are told to make it airtight. they wont . It costs alot more to do so.

brendankelly

gsxr1 wrote: »

The groves in the velux are not ment to make the system draft free. . Its simply to locate the plaster board neatly.

It is also hardly a plasterers fault that the plaster breaks down and cracks in a new build.

I cant believe experienced people would make crazy comments like it should be illegal . :rolleyes: (end Quote)


The plaster work in those pictures is an absolute disgrace and the person responsible should not be allowed call himself a plasterer.

The faults in the picts are the plasterers fault. All cracks and faults excepts structural cracks and faults are the responsibility and fault of the plasterer and I can see no structural faults or cracks in these pictures.

Whose fault do you think it is when plaster breaks down of cracks in any building????

AckwelFoley

brendankelly wrote: »

gsxr1 wrote: »

The groves in the velux are not ment to make the system draft free. . Its simply to locate the plaster board neatly.

It is also hardly a plasterers fault that the plaster breaks down and cracks in a new build.

I cant believe experienced people would make crazy comments like it should be illegal . :rolleyes: (end Quote)


The plaster work in those pictures is an absolute disgrace and the person responsible should not be allowed call himself a plasterer.

The faults in the picts are the plasterers fault. All cracks and faults excepts structural cracks and faults are the responsibility and fault of the plasterer and I can see no structural faults or cracks in these pictures.

Whose fault do you think it is when plaster breaks down of cracks in any building????

The marks in the plaster mentioned earlier are brush strokes from paint, not srom troweling or lack of.

Cracks do appear, sometimes structural, othertimes from slabs that are poorly fitted, actually i can give a dozen exmples of how cracks can appear without it being the plasterers fault,

In this instancem you cant actually use scrim tape , you can only use that in corners or on the joint of 2 boards, not where it meets a window.

The little hole you see at the bottom of the window in the corner, you cant skim into that, im sure you could push some skim in and brush it in , but i promise you when it sries and with integral structural movment, it will pop out

gsxr1

For clarity.

You look as if you are quoting me in that last post. Which is not the case.

brendankelly

Brush strokes??/ If they are, they are yard brush strokes.

There are only 2 types of cracks. Structural cracks that my first year apprentice would identify and cracks that are due to stupidity, stupidity, ignorance, more stupidity and 8 different combinations of stupidity and ignorance.

Real plasterers have (although they will never admit to having one) a special tool to plaster into corners and small areas. It is known by trades men as a small tool.

Why could you not use scrim here??. Was it because your price was so low that you could not afford it??.

gsxr1

again with the drama.

Just caulk it.

fixed.

mfceiling

Exactly as above....caulk it.

Snyper is right........they are brush marks from the painter (how the hell would a plasterers trowel leave a mark like that??)

Also brendan........i see you talk about one cheap coat of plaster.
Gypsum skim is a one coat finish that is applied, then trowelled, then trowelled again, then allowed to "go off" then wet with a brush and then trowelled to finish.
Is a 2 coat some other kind of plaster? - i've worked with plasterers in here and in england and i've never seen gypsum plaster put on top of a coat of plaster...just curious as i remember you saying it before.

saltandpepper10

mfceiling wrote: »

Exactly as above....caulk it.

Snyper is right........they are brush marks from the painter (how the hell would a plasterers trowel leave a mark like that??)

Also brendan........i see you talk about one cheap coat of plaster.
Gypsum skim is a one coat finish that is applied, then trowelled, then trowelled again, then allowed to "go off" then wet with a brush and then trowelled to finish.
Is a 2 coat some other kind of plaster? - i've worked with plasterers in here and in england and i've never seen gypsum plaster put on top of a coat of plaster...just curious as i remember you saying it before.

skimming in ireland is always a two coat process,and i am a carpenter would have thought everyone on the buildings would have known this watch more closely people.also its good practise to put the taper edge into velux grove if you can,those pictures are an unaceptable finish imo

brendankelly

Very interesting comments from people that are supposed to be giving others good advice. Your comments are an indication of the work manship you will tolerate. I was a plastering foreman some years back and if someone left work like that he would be shown the gate. I will let some real painter respond to your other point.

Also mf ..... I have heard of cowboys that are trying to get away with cheap one coat plastering jobs but none ever tried that with me because I would spot a cowboy before he would even reached the gate. I am curious about the people that you worked with and for some reason an old proverb is in my mind. It goes something like ""show me your company and I will tell you what you are"".

gsxr1

brendankelly wrote: »

Very interesting comments from people that are supposed to be giving others good advice. Your comments are an indication of the work manship you will tolerate. I was a plastering foreman some years back and if someone left work like that he would be shown the gate. I will let some real painter respond to your other point.

Also mf ..... I have heard of cowboys that are trying to get away with cheap one coat plastering jobs but none ever tried that with me because I would spot a cowboy before he would even reached the gate. I am curious about the people that you worked with and for some reason an old proverb is in my mind. It goes something like ""show me your company and I will tell you what you are"".

And your advise to fix the problem is

Drumroll......... Arrest the plaster as you made it illegal.


Your comments are not advise . They are simply a stab at the plasterer who did the job. Not to mention your stab at everyone else!


The OP simply wanted advise on stopping the draft????

Shooting the builder is not really an option.

brendankelly

The OP has gotten advice that I did not disagree with and my advice is to make the person responsible fix his mess and to others reading this to be more cautious before they make their final payment.
I pay a lot of money for my insurance and my liabilities is 3 million if one of my men gets killed or injured and a massive 13 million if I am sued for bad workmanship. There was never a claim against my insurance so I suspect there were claims against other contractors to have the premiums so high. The person that did this job was not a plasterer, he was a cowboy that is costing me money on my insurance premiums.

My question to you gsxr1 . Would the workmanship in those pictures be acceptable to you?????/

mfceiling

brendankelly wrote: »

Very interesting comments from people that are supposed to be giving others good advice. Your comments are an indication of the work manship you will tolerate. I was a plastering foreman some years back and if someone left work like that he would be shown the gate. I will let some real painter respond to your other point.

Also mf ..... I have heard of cowboys that are trying to get away with cheap one coat plastering jobs but none ever tried that with me because I would spot a cowboy before he would even reached the gate. I am curious about the people that you worked with and for some reason an old proverb is in my mind. It goes something like ""show me your company and I will tell you what you are"".

Self employed the last 5 years but i have never seen skim put on in "2" coats.
One of the companies i was a foreman for have just won the Quality Gold Award for the "Best Dry lining Commercial Contract over £1m" at the FPDC awards in London....and although a lot of their work is taping and jointing they have about 15-20 skimmers on the cards and again i never saw 2 coats of skim being applied.
Does the skim go on then after it has been trowelled and made reasonably dry then another wet coat of skim go on?
I am genuinely curious as it seems every plasterer from donegal to cork only uses one coat!!
My own experience is metal framed suspended ceilings and metal stud partitions, bulkheads etc...used to having skimmers work after me...no complaints so far!!

brendankelly

mfceiling wrote: »

Self employed the last 5 years but i have never seen skim put on in "2" coats.
One of the companies i was a foreman for have just won the Quality Gold Award for the "Best Dry lining Commercial Contract over £1m" at the FPDC awards in London....and although a lot of their work is taping and jointing they have about 15-20 skimmers on the cards and again i never saw 2 coats of skim being applied.
Does the skim go on then after it has been trowelled and made reasonably dry then another wet coat of skim go on?
I am genuinely curious as it seems every plasterer from donegal to cork only uses one coat!!
My own experience is metal framed suspended ceilings and metal stud partitions, bulkheads etc...used to having skimmers work after me...no complaints so far!!

Correction, Every cowboy only uses one coat. Every Plasterer uses 2 coats.

The reason is that gypsum plaster replaced lime plaster which was breathable and gypsum is not naturally breathable and if not done properly you could have problems with mould etc after time. The reason for 2 coats is that you apply one coat and when it is about to go off you apply the second coat. As the first coat is drying the drying out process makes the second coat porous and more breathable and the trowel can give a smooth finish without glazing the plaster. If the plaster is glazed you will have problems.

AckwelFoley

The second coat is called "filling in the fat"

Old school plasterers used a wooden trowel, akin to the pvc float -

I dont, i use the pvc float, i to be honest havent seen alot of plasterers use the pvc float for the second application, but i do as i find its better (for me) at evening out the skim.

Brendan, i still believe from what i can see that they are brush strokes - i dont see how a trowel can make brush like marks.

As for the scrim - why would i not use scrim, its cheap -but where or moreover how do you apply scrim tape to a window?

thekooman

many thanks for all the comments folks.
the marks on the plaster are brush marks from the paint.
the cracks between the velux and plasterboard i would put down to general movement between timber and plaster... the plasterer actually was very good. how you finish between the velux and plasterboard i don't know.

I tried the tec7 last week and it looks good. I might try the painters caulk later... got a tube for filling between skirting board and wall anyways.
I've used masking tape to keep the tec7/caulk off the timber of the velux.

AckwelFoley

thekooman wrote: »

many thanks for all the comments folks.
the marks on the plaster are brush marks from the paint..

Thought so.

thekooman

snyper wrote: »

Thought so.

meself and the wife thought we were the best painters in the world...
:rolleyes:

gsxr1

thekooman wrote: »

many thanks for all the comments folks.
the marks on the plaster are brush marks from the paint.
the cracks between the velux and plasterboard i would put down to general movement between timber and plaster... the plasterer actually was very good. how you finish between the velux and plasterboard i don't know.

I tried the tec7 last week and it looks good. I might try the painters caulk later... got a tube for filling between skirting board and wall anyways.
I've used masking tape to keep the tec7/caulk off the timber of the velux.

You might have problems now with the tec 7. I pretty sure it wont take paint.

And it is very hard to remove .

AckwelFoley

gsxr1 wrote: »

You might have problems now with the tec 7. I pretty sure it wont take paint.

And it is very hard to remove .

http://www.contec7.co.uk/tec7-uses.htm

You can paint over it apparently

brendankelly

saltandpepper10 wrote: »

skimming in ireland is always a two coat process,and i am a carpenter would have thought everyone on the buildings would have known this watch more closely people.also its good practise to put the taper edge into velux grove if you can,those pictures are an unaceptable finish imo

Of course it is a 2 coat process. Only cowboys try to get away with one coat.

brendankelly

mfceiling wrote: »

Self employed the last 5 years but i have never seen skim put on in "2" coats.
One of the companies i was a foreman for have just won the Quality Gold Award for the "Best Dry lining Commercial Contract over £1m" at the FPDC awards in London....and although a lot of their work is taping and jointing they have about 15-20 skimmers on the cards and again i never saw 2 coats of skim being applied.
Does the skim go on then after it has been trowelled and made reasonably dry then another wet coat of skim go on?
I am genuinely curious as it seems every plasterer from donegal to cork only uses one coat!!
My own experience is metal framed suspended ceilings and metal stud partitions, bulkheads etc...used to having skimmers work after me...no complaints so far!!

I find it very disturbing that someone could get the job of foreman that did not know that plaster should be put on in 2 coats. And even more disturbing that there are so many cowboys doing sub standard work and getting away with it.

paddy147

FFS lads,take it somewhere else.

The op asked how to seal the gap around a Velux and keep draughts out,not about how to plaster a wall or ceiling or how many coats of plaster should be done when plastering.

Give it a rest now.

brendankelly

thekooman wrote: »

many thanks for all the comments folks.
the marks on the plaster are brush marks from the paint.
the cracks between the velux and plasterboard i would put down to general movement between timber and plaster... the plasterer actually was very good. how you finish between the velux and plasterboard i don't know.

I tried the tec7 last week and it looks good. I might try the painters caulk later... got a tube for filling between skirting board and wall anyways.
I've used masking tape to keep the tec7/caulk off the timber of the velux.

With respect, I would not rate the plasterwork as good. There should be no movement between the plasterboard and the velux and if there is your velux is not fitted properly. If there was movement the plasterer would have spotted it and either fixed it or brought it to your attention.

There is a grove in velux where the plaster board fits in to and as someone else stated it is designed for the tapered edge but an off cut can be filed down to fit also. There should be no space between the plasterboard and the velux.

mfceiling

brendankelly wrote: »

I find it very disturbing that someone could get the job of foreman that did not know that plaster should be put on in 2 coats. And even more disturbing that there are so many cowboys doing sub standard work and getting away with it.

Don't be disturbed brendan.......i was in charge of the lads putting up the suspended ceilings and the metal stud partitions.
I had nothing to do with the plasterers.....just my observation that i thought plaster was a one coat process.
I've never had any trouble with my end of work and i've laid out jobs from intel to new schools in london......and still i get calls from people i worked with asking me to work for them so i think i've done something right over the past 10 or 12 years.
As the saying goes "when i leave for work in the morning i leave my horse at the house and cowboy hat on the table";)

brendankelly

mfceiling wrote: »

Don't be disturbed brendan.......i was in charge of the lads putting up the suspended ceilings and the metal stud partitions.
I had nothing to do with the plasterers.....just my observation that i thought plaster was a one coat process.
I've never had any trouble with my end of work and i've laid out jobs from intel to new schools in london......and still i get calls from people i worked with asking me to work for them so i think i've done something right over the past 10 or 12 years.
As the saying goes "when i leave for work in the morning i leave my horse at the house and cowboy hat on the table";)

Well at least you now have learned how plastering should be done and you might correct the statement you made on the costs forum where you stated the cost for skimming was 5 e per sq meter.

gsxr1

paddy147 wrote: »

FFS lads,take it somewhere else.

The op asked how to seal the gap around a Velux and keep draughts out,not about how to plaster a wall or ceiling or how many coats of plaster should be done when plastering.

Give it a rest now.

im surprised he hasn't try to sell him a bag of lime plaster lol:D

brendankelly

gsxr1 wrote: »

im surprised he hasn't try to sell him a bag of lime plaster lol:D

The Op has a draught at his velux window and is been given ""advice""" by people that know nothing about plastering and you find this a reason to make a joke about it. (I do not think its funny)

If wind can get in so can moisture and it is not rocket science to know that moisture and rafters/plaster board do not mix and the advice is to cover up the problem and hope it goes away.

Also I do not try to sell bags of lime or lime plaster. I do not do gypsum skimming and it appears that there were only 3 people on this thread that knew how before this topic started.

gsxr1

OP wind can get through a velux flashing kit and stay completely dry .

Just seal it internally Your painting is grand. And your house is not going to fall over.

Brendan is just going into one .


Again.

eosirl08.

gsxr1 wrote: »

again with the drama.

Just caulk it.

fixed.

please listen to this man and the problem will be solved its not rocket science

DonalK1981

That window should only let in a draught if it's open! I'd be pretty annoyed if I paid to get nice windows fitted and there was a problem with them. Get the builder to sort the issue out. No way is it acceptable you to have more expense above what was already paid.

brendankelly

Of course it should not be acceptable and the response shows the contempt some have for the self build/DIY people. ""Awe sure it will be grand luv, a bit of silly cone will fix it, velux windows are designed to let in a bit of air but they are guaranteed to keep snow out in June"". etc etc.

On a Zero energy house. The test after the fermecell boarding and plastering was done showed a 10 mm sq air escape in the entire house. The house must have 20 windows and doors. That would be at max a half of a sq mm gap per window and door, not to even take into account of the other areas like water pipes etc.

saltandpepper10

fair play to you brendan you are obviously passionte about your trade and this is to be admired,far too many yahoos going about paticularly in the wet trades

brendankelly

Thanks saltandpepper.

I feel sorry for the self build/ DIY people. They come on these forums expecting good advise only to be told that windows should allow draughts in when fitted. To tell someone wind can get through without wetting timber and plasterboard beggars belief. Soon the mould will appear and then the advice will be to spray it with chemicals. My heart goes out to the victims of these con men.

heinbloed

Since the load exposure differs for window and wall/roof there will be no airtight sealing with the shown solution. Go to the Velux company and ask them, or any real window installer/carpenter.
Either the loads are equalized (spread to frame and background), for example by counterbatting, or a flexible sealer has to be installed between frame and wall.
The plaster-on-timber method is an amateur's mistake. Not suitable for an airtight sealing.

The most common solution in the shown case (i.e. the fastest and cheapest) is compression tape covered with mastix.

DonalK1981

heinbloed wrote: »

Since the load exposure differs for window and wall/roof there will be no airtight sealing with the shown solution. Go to the Velux company and ask them, or any real window installer/carpenter.
Either the loads are equalized (spread to frame and background), for example by counterbatting, or a flexible sealer has to be installed between frame and wall.
The plaster-on-timber method is an amateur's mistake. Not suitable for an airtight sealing.

The most common solution in the shown case (i.e. the fastest and cheapest) is compression tape covered with mastix.

There is a more fair way of getting this sorted. Return to the original cowboys, tell them if the work is not completed to the proper standard that there will be a court case. Their workmanship left a lot to be desired. If left like this in a few years dampness etc. would or could cost quite a bit to repair. By that time the chance of legal action will have expired...

heinbloed

Agreed on, DonalK1981.

The OP wrote:

the cracks between the velux and plasterboard i would put down to general movement between timber and plaster... the plasterer actually was very good. how you finish between the velux and plasterboard i don't know.

Who is to blame?

The setting of the window should include the airtight sealing. Two trade persons not knowing about each other's plans are hardly pulling the same cord.
The OP should have prepared the correct detailing for each trade. Velux might have these available, a reference to these details for both trades (carpenter AND plasterer) would have saved a lot of work.

brendankelly

I think that everyone except mfceilings, gsxr1 and snyper agrees the workmanship is poor and silly cone is nor the solution.

I suspect this is a self build so this rules out legal action. If the people that did this work were local they might repair it with the threat of legal action. If the velux was fitted properly there is no way there would be a draught see http://www.velux.ie/private/get_inspired/replacement/tradetoolkit/bestpractice/installationinslate Other than that the OP should get a proper carpenter to fit the velux properly with the air tight seal and a plasterer to plaster it properly.

mfceiling

Get you facts straight brendan......nowhere in any of my posts did i mention "bad workmanship".
Yes the bush marks when painting leave a lot to be desired but as for the original fitting of the velux - that's for the OP and whoever fitted it to come to an agreement.
Please don't post rubbish telling me what i said - read the posts - it's not that difficult.

gsxr1

brendankelly wrote: »

I think that everyone except mfceilings, gsxr1 and snyper agrees the workmanship is poor and silly cone is nor the solution.

I suspect this is a self build so this rules out legal action. If the people that did this work were local they might repair it with the threat of legal action. If the velux was fitted properly there is no way there would be a draught see http://www.velux.ie/private/get_inspired/replacement/tradetoolkit/bestpractice/installationinslate Other than that the OP should get a proper carpenter to fit the velux properly with the air tight seal and a plasterer to plaster it properly.

You are over reacting Brendan.

With out inspecting the work personally you are telling a lad to get a chippy to rip out all the velux which would involve extensive internal and external construction work.. Thats a lot of disruption in a persons life. I will not speculate on the problem as I am not there to look at it.
Im all for doing a job correctly and practice it every day.
But weighting up a small draft that can be simply cured with chalking to a scaffolding set up, tiles and felt up. plaster board and plaster destruction, new flashing kit, new installation with all the cost and dirt that goes with it.

DonalK1981

gsxr1 wrote: »

You are over reacting Brendan.

With out inspecting the work personally you are telling a lad to get a chippy to rip out all the velux which would involve extensive internal and external construction work.. Thats a lot of disruption in a persons life. I will not speculate on the problem as I am not there to look at it.
Im all for doing a job correctly and practice it every day.
But weighting up a small draft that can be simply cured with chalking to a scaffolding set up, tiles and felt up. plaster board and plaster destruction, new flashing kit, new installation with all the cost and dirt that goes with it.

Pity someone like you or the more qualified persons didn't undertake the job and do it properly in the first place, then the OP might not have to scaffold, set up, tiles and felt up. plaster board and plaster destruction, new flashing kit, new installation with all the cost and dirt that goes with it, as you say. I believe whoever fitted it should be made, at their expense, fix the problem. A court might even make them pay punitive damages, for the disruption caused by the shoddy work leading to the disruption in the OP's life.

AckwelFoley

It fine to tell someone to do all that, but without doing a site visit im not going to tell someone to do that, when in reality, they're not going to do it.


The window maybe poorly fitted, certainly the plasterboaard is not covering the window enough, however without being out on the site the draft may not be comming from outside,if less likley, but not impossible that the draft is internal from the different air temp in the attic / roof space and living area, its also possible that there is a faulty vent in the window, or that the seal in the window frame is damaged, so when closed its still letting in air.

With the best will in the world, i cannot blaim any one specific person until i was actually on site, it could be the roofer, the slabber or the plasterer or the window itself

brendankelly

mfceiling wrote: »

Get you facts straight brendan......nowhere in any of my posts did i mention "bad workmanship".
Yes the bush marks when painting leave a lot to be desired but as for the original fitting of the velux - that's for the OP and whoever fitted it to come to an agreement.
Please don't post rubbish telling me what i said - read the posts - it's not that difficult.

You said it all when you stated that you are aligned with people that do not know how to plaster. You also stated that you knew skimmers that work for 5 e a meter.
Ryanair tradesmen and a few mushroom contractors are all that would work for that.

brendankelly

snyper wrote: »

It fine to tell someone to do all that, but without doing a site visit im not going to tell someone to do that, when in reality, they're not going to do it.


The window maybe poorly fitted, certainly the plasterboaard is not covering the window enough, however without being out on the site the draft may not be comming from outside,if less likley, but not impossible that the draft is internal from the different air temp in the attic / roof space and living area, its also possible that there is a faulty vent in the window, or that the seal in the window frame is damaged, so when closed its still letting in air.

With the best will in the world, i cannot blaim any one specific person until i was actually on site, it could be the roofer, the slabber or the plasterer or the window itself

Jesus it get worse. The draft is coming from the attic/roof space.

I do not have to do a site visit to know there is no attic/roof space over a velux window.

God help us.