Rendering on timber/ EML

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RickM

New Member
Hi All

I am hoping to get a little bit of guidance.

I am having a loft conversion done and the chippies have got the dormer ready for rendering. I have a timber external skin which they have covered with roofers underlay felt and the stainless steel EML.

I got in to reading about rendering of timber frames and it states that there should be a cavity between the rendering and the timber. It is too late to do this now.

I have 2 questions:

1. Is there any additional measures I could take to protect the timber/ply

2. What mix and how many coats of rendering should I use? I wasn’t looking to use ready mix render.

Many thanks

Rick
 

essexandy

The Lake Governor
Hi All

I am hoping to get a little bit of guidance.

I am having a loft conversion done and the chippies have got the dormer ready for rendering. I have a timber external skin which they have covered with roofers underlay felt and the stainless steel EML.

I got in to reading about rendering of timber frames and it states that there should be a cavity between the rendering and the timber. It is too late to do this now.

I have 2 questions:

1. Is there any additional measures I could take to protect the timber/ply

2. What mix and how many coats of rendering should I use? I wasn’t looking to use ready mix render.

Many thanks

Rick
You're as clueless as your chippies. Leave the job to those that know how.
 

themucky1

Well-Known Member
Hi All

I am hoping to get a little bit of guidance.

I am having a loft conversion done and the chippies have got the dormer ready for rendering. I have a timber external skin which they have covered with roofers underlay felt and the stainless steel EML.

I got in to reading about rendering of timber frames and it states that there should be a cavity between the rendering and the timber. It is too late to do this now.

I have 2 questions:

1. Is there any additional measures I could take to protect the timber/ply

2. What mix and how many coats of rendering should I use? I wasn’t looking to use ready mix render.

Many thanks

Rick
This job isn’t near Wolverhampton by any chance is it?
 

bobski

Well-Known Member
Hi All

I am hoping to get a little bit of guidance.

I am having a loft conversion done and the chippies have got the dormer ready for rendering. I have a timber external skin which they have covered with roofers underlay felt and the stainless steel EML.

I got in to reading about rendering of timber frames and it states that there should be a cavity between the rendering and the timber. It is too late to do this now.

I have 2 questions:

1. Is there any additional measures I could take to protect the timber/ply

2. What mix and how many coats of rendering should I use? I wasn’t looking to use ready mix render.

Many thanks

Rick


Are you rendering it yourself? Or trying to get it ready for someone?
 

Runswithscissors

Private Member
If you want it rendered.... take the eml off, fit vertical battens and then a specialist directly applied render carrier board - then a bespoke modern thin coat render

you don’t want a brittle, home mix sand and cement direct to a timber frame dorma element that will move and the render then potentially fails on a roof you cannot get to later
... or, you might be lucky and the render direct to the timber will last and trap moisture in the timber, you will then have structural problems in the timber dorms later instead

By all means, give me a shout and I will guide you - I look after the Knauf Aquapanel Outdoor directly applied render carrier board

Also, per earlier posts - get a contractor in who knows how and has done this before... see their work before you appoint them (before your builder tells you he does it all the time!)

Good Luck
Richard Lord
Knauf
Rlord@knauf.co.uk
07918 766577
 

Rigsby

TPF Special Forces
The chippies have done it the way it used to be done 15+ years ago. It can work with the right mix and practice which it sounds like your plasterer hasnt got but even then you will have a brittle render on a flexible substrate so cracking might be an issue. The felt will probably be the modern breathable felt but you still risk condensation on the dew point so not ideal. As said above, if space permits fit exterior aquapanel and a thin coat system for peace of mind. You will need some vent but not too big a gap, think about wind and suction.
 

Runswithscissors

Private Member
885C1BCB-C7C0-4CE2-BE20-0F7D76EEA4FE.jpeg
 

bobski

Well-Known Member
The chippies have done it the way it used to be done 15+ years ago. It can work with the right mix and practice which it sounds like your plasterer hasnt got but even then you will have a brittle render on a flexible substrate so cracking might be an issue. The felt will probably be the modern breathable felt but you still risk condensation on the dew point so not ideal. As said above, if space permits fit exterior aquapanel and a thin coat system for peace of mind. You will need some vent but not too big a gap, think about wind and suction.


Most of my days are spent on that last sentence.
 

RickM

New Member
Thanks for the replies, Richard I might give you a call when I get a chance a bit later. I have a few more questions:


  1. Do I need vertical battens or can I fix cement board straight to gable end timbers? (They have already completed soffits and facia etc so I can’t afford for the walls to come out too far)
  2. If I use specialist render, will rest of house and garden walls that I am planning to render need to be the same (house is currently pebble dash which I am planning to back off before rendering)?
  3. Can I just use breathable render on the timber like may be done on old houses with no cavity

    I have added a couple of photos but it was a bit dark this morning when I left
 

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ChrispyUK

Well-Known Member
Thanks for the replies, Richard I might give you a call when I get a chance a bit later. I have a few more questions:


  1. Do I need vertical battens or can I fix cement board straight to gable end timbers? (They have already completed soffits and facia etc so I can’t afford for the walls to come out too far)
  2. If I use specialist render, will rest of house and garden walls that I am planning to render need to be the same (house is currently pebble dash which I am planning to back off before rendering)?
  3. Can I just use breathable render on the timber like may be done on old houses with no cavity

    I have added a couple of photos but it was a bit dark this morning when I left

might be better with the lights on!
 

Runswithscissors

Private Member
Thanks for the replies, Richard I might give you a call when I get a chance a bit later. I have a few more questions:


  1. Do I need vertical battens or can I fix cement board straight to gable end timbers? (They have already completed soffits and facia etc so I can’t afford for the walls to come out too far)
  2. If I use specialist render, will rest of house and garden walls that I am planning to render need to be the same (house is currently pebble dash which I am planning to back off before rendering)?
  3. Can I just use breathable render on the timber like may be done on old houses with no cavity

    I have added a couple of photos but it was a bit dark this morning when I left

Good talking with you today Ricky - hopefully assisted you with the boarded render option

quick answers to your posted questions:
Need battens for ventilation for timber frame to breath
The modern thin coat render basecoat can be flattened and painted to look like painted S&C - as dorma and gable end, they are not right alongside S&C to block work, so not going to be directly compared
Like S&C renders, breathable old school renders - like lime renders - are heavy and brittle, so while breathable for the timber frame, at risk of cracking and failure like the S&C

Feel free to get back in touch if I can assist further

Dick Lord
Knauf
07918 766577
Rlord@knauf.co.uk
 

RickM

New Member
Good talking with you today Ricky - hopefully assisted you with the boarded render option

quick answers to your posted questions:
Need battens for ventilation for timber frame to breath
The modern thin coat render basecoat can be flattened and painted to look like painted S&C - as dorma and gable end, they are not right alongside S&C to block work, so not going to be directly compared
Like S&C renders, breathable old school renders - like lime renders - are heavy and brittle, so while breathable for the timber frame, at risk of cracking and failure like the S&C

Feel free to get back in touch if I can assist further

Dick Lord
Knauf
07918 766577
Rlord@knauf.co.uk
Thanks Richard, you’ve been a massive help and thanks to others who tried to help too.
 
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