Sealing and repairing where uPVC window frames meet mortar (external)

[Oxbow16]

Hi all

 

I've got a couple of question about this if anyone could spare a moment to set me on the right tracks.

 

1. I've got a lot of uPVC windows with no sealant where the frame meets the mortar. The gaps are small, under a mm I'd say. Are they ok as is or would it be best to seal them? If sealing is needed, what would be best to use?

 

2. On a couple of these windows chunks of mortar have fallen away. Should I repair with mortar or something else? If using mortar, what product / mix do I need?

Some pictures of both things below.

 

Many thanks

 

 

 

 

 

 

[Mr Punter]

It looks like the windows were foamed, then mortar over the foam.  You could run a bead of silicone down if you can finish it neatly.  The low modulus stuff may be good for this.  Whare you have to bit of missing mortar, fill with fresh mortar first.

[Oxbow16]

Thanks @Mr Punter

 

As a complete novice can anyone guide me through what I need to do to replace the mortar please?  I haven't done much of this kind of thing before.  

 

As for the sealant, I have used Geocel The Works in the past and that seemed to do the job great.  I used it where timber windows joined the walls, and some of the gaps were huge.  It stood the test of time though and never had any issues with it.  Would that be ok in this application or would low modulus silicone be better?  

 

Cheers

[tonyshouse]

I would clear silicone to the render, silicone nice where mortar damaged/missing then repair with local sand and cement 4:1 

 

then after a week silicone that too 

[Onoff]

I'd maker good the mortar then CT1 those gaps and baby wipe off. 

[Pete]

18 minutes ago, Onoff said:

I'd maker good the mortar then CT1 those gaps and baby wipe off. 

I used Ct1 to seal some of my exterior windows to the Parex render and quite a few have cracked at the sill/ reveal junction so I think it is not flexible enough? My frames are  aluclad and get full sun in summer so I expect the exp/cont of the sill is the problem. Bought some silkaflex and going see how that goes 

[Onoff]

1 hour ago, Pete said:

I used Ct1 to seal some of my exterior windows to the Parex render and quite a few have cracked at the sill/ reveal junction so I think it is not flexible enough? My frames are  aluclad and get full sun in summer so I expect the exp/cont of the sill is the problem. Bought some silkaflex and going see how that goes 

 

Fair point that. You can get "brown" frame sealant. It's achieving a nice bead is the issue. Easy to make a crap job. 

 

https://www.toolstation.com/window-door-external-frame-sealant-300ml/p76921?

 

I used an Evostik product about 35 years ago on a prefab garage and am sure it said "good for 25 years" on the tube. I replaced a door by cutting and dropping in gravel boards. Irregularly repainted with Sandtex the "silicone" or whatever it was is still good.

Edited December 15, 2020 by Onoff

[Mr Punter]

With the mortar, there is only a tiny bit needed.  Apply this and leave it a couple of days before you silicone.

https://www.toolstation.com/toupret-touprelith-f-exterior-masonry-repair-filler/p35114

 

For the silicone, you could run some masking tape 2mm either side of the join (a piece on the mortar and a piece on the frame) and use a mastic gun to apply a bead of silicone.  Smooth it off with a finger.  Clean your hands, then remove the masking tape.

https://www.toolstation.com/premium-building-silicone-310ml/p97204