When is a Shadow Gap acceptable?

[Russell griffiths]

I prefer this type of finish, as previously mentioned I would hate to run plasterboard to the floor and get it damaged by kids toys, hoover. 

What about it getting damaged by say water from a steam mop or something similar. 

[Dudda]

11 hours ago, JSHarris said:

How hard would it be to come up with a gadget to neatly grind out shadow gaps after plastering, I wonder?  The trick would be finding a tool that would cut neatly, leaving a very tidy edge, but I bet it would be a winner if you could make it work.  The time saving could be massive, and significantly reduce the cost, and allow more adventurous use of gaps as design features.

Over time the straight edge would chip and become unsightly. The bead gives a minor bit of protection.

[Stephen Aitch]

Hi all,

Architect has recommended a shadow gap on our new build.

 

On GF we are having polished concrete, so I am happy it will work well.

 

On 1F we are fitting carpets. Struggling to find images of carpet with shadow gap.  Any views on whether this will work pls?

[Tom]

Interestingly Stephen, we want shadow gaps with our concrete floor but our architect is warning against. He's worried that any irregularity/wavyness in the floor will be too easy to see with unforgiving shadow gaps. We're planning a power floated finish rather than polished.

Are you happy you will be able to achieve a crisp finish - and if so can you share how?!

[Stephen Aitch]

On 18/09/2020 at 18:51, Tom said:

Interestingly Stephen, we want shadow gaps with our concrete floor but our architect is warning against. He's worried that any irregularity/wavyness in the floor will be too easy to see with unforgiving shadow gaps. We're planning a power floated finish rather than polished.

Are you happy you will be able to achieve a crisp finish - and if so can you share how?!

Hi Tom, sorry - just seen this now!

The concrete floor is being installed first - Lazeby insisted on this.  That should derisk builders setting the shadow gap at irregular intervals.  Lets hope it works!  I will keep you posted.  For the first floor we are now going with skirting - to help pin our accoustic flooring down.

 

 

[SiBee]

Shadow gaps = home for spiders to live?

Ours is a typical newish build so nothing like the levels of insulation aimed for on here. Now that the colder months are here we seem to find more bugs and insects inside the home? Before you question it yes we are clean and hygiene conscious ?

love the idea of shadow gaps but hate the idea of nooks n crannies for  dust and stuff to gather.

[flanagaj]

On 02/01/2018 at 10:32, IanR said:

We've put shadow gaps at all floor-to-wall joints and around all door linings in the living areas of the house where we have hard floors. We haven't used them in carpeted or tiled areas.

 

We've used them for their aesthetic. We have minimal steps/rebates/shoulders etc. around any features and have tried to keep that theme running throughout the house. 

 

We have used a very simple skirting/architrave in carpeted areas. Our logic to this was that the more hoovering required in these areas would risk damage to the bottom edge of plastered walls if we used a shadow gap against carpet. We also wanted a slightly softer look in the bedroom areas.

 

Some thought needs to go into how it is best to deliver shadow gaps around door linings. Two schools of thought: 1. temporary ply liners in to board and plaster to, then remove ply liners and fit final liners, or. 2. fit final liners and mask/protect then plaster up to them.

 

We went with 1. and found we got some cracking around the liners as we fitted the final door liners. As the liners were screwed in they pushed against the edge of the shadow gap trim and the plaster cracked behind it. This happened on a couple of doors and required chipping out the cracked area and filling. If it was a painted or varnished finish to the door liner I'd try 2. next time, but natural, lacquered or oiled finish and I'd stick with 1. to avoid staining on the finished door liner.

 

We used Qic Trims

https://www.qic-trims.com/product/type-r/

 

After decoration you will need to mastic the gap from the edge of the shadow gap trim to the floor/door liner. There will always be gaps that need finishing. 

 

Shadow gaps do seem to mean different things to different people. To me they are a small rebate at wall-to-floor and wall-to-frame junctions that disguises the actual joint in a shadowed area. I know they are also used in conjunction with skirting to create a rebate above the skirting, but to me that's not a "shadow" gap.

 

Our version of a shadow gap:

 

 

 

That is very nice!

[flanagaj]

So this got me thinking last night to see whether there was a good solution to installing these around door linings.  I came up with the below approach.   If fitting them to stud walls then the dimensions of the wall will be 95mm and therefore your rebates that you cut with the fine kerf will be straightforward.  Block walls might be trickier.  it all depends on how and who fits the trims to the stud work or blockwork.  

 

 

[crispy_wafer]

Just did a web search for the timber profile that @Russell griffiths posted as I love that.  Just enough of a mix between modern and traditional.  AGS Skirting boards - AGS Systems | flush doors and skirting boards (ags-systems.info), theres a few how to youtube construction videos aswell which may be useful.

[ToughButterCup]

1 hour ago, flanagaj said:

...  it all depends on how and who fits the trims to the stud work or blockwork.  ...

 

Every last bit of research I have done about this issue makes the same point. 

 

Here's Scott Brown (Kiwi carpenter) on the subject  - well worth following

 

 

[markharro]

On 02/01/2018 at 20:00, Trw144 said:

One thing to consider with shadow gaps is the floor finishes - downstairs we had tiles which is fine and basically we had the house tiled and then boarded/skimmed afterwards. Upstairs we had to install the engineered oak flooring after the plastering due to the risks of damage to the floor (general mess plus high moisture content due to wet plaster damaging the floor) - this means they had to leave an exact gap to allow the floor to be laid, with the floor ending up touching the bottom of the shadow gap profile. 

Hi @Trw144 can I ask how you laid the engineered flooring after you had the walls completed as I am trying to puzzle out the same thing now. . I understand the mechanics of fixing the wall board down to the correct height so that the floor then slides under and leaves the desired height of shadow gap. My query is how do you set the short board joins? The long lengths are fine as they are fully exposed other than the 10mm or so tucked under the shadow gap. But we will be using mixed lengths of 1.8 - 3m for a floor about 4m x 4m and so the boards need to be joined to get across the full 4m length? I think the standard way to do this is to use a pull bar and hammer but that means somehow getting the end of the bar under the far edge of the board which is under your plasterboard if you see what I mean? While this might be possible at one end what about the other length that you are butting on to? How does that stay in one place as you hammer the other piece? Would it not hammer in tight under your plasterboard on the other wall and mean you have no expansion gap at that side? Maybe use 2 pull bar left and right and two people hammering at the same time?

[markharro]

On 02/01/2018 at 20:00, Trw144 said:

One thing to consider with shadow gaps is the floor finishes - downstairs we had tiles which is fine and basically we had the house tiled and then boarded/skimmed afterwards. Upstairs we had to install the engineered oak flooring after the plastering due to the risks of damage to the floor (general mess plus high moisture content due to wet plaster damaging the floor) - this means they had to leave an exact gap to allow the floor to be laid, with the floor ending up touching the bottom of the shadow gap profile. 

Hi @Trw144 can I ask how you laid the engineered flooring after you had the walls completed as I am trying to puzzle out the same thing now. . I understand the mechanics of fixing the wall board down to the correct height so that the floor then slides under and leaves the desired height of shadow gap. My query is how do you set the short board joins? The long lengths are fine as they are fully exposed other than the 10mm or so tucked under the shadow gap. But we will be using mixed lengths of 1.8 - 3m for a floor about 4m x 4m and so the boards need to be joined to get across the full 4m length? I think the standard way to do this is to use a pull bar and hammer but that means somehow getting the end of the bar under the far edge of the board which is under your plasterboard if you see what I mean? While this might be possible at one end what about the other length that you are butting on to? How does that stay in one place as you hammer the other piece? Would it not hammer in tight under your plasterboard on the other wall and mean you have no expansion gap at that side? Maybe use 2 pull bar left and right and two people hammering at the same time?

[markharro]

On 02/01/2018 at 20:00, Trw144 said:

One thing to consider with shadow gaps is the floor finishes - downstairs we had tiles which is fine and basically we had the house tiled and then boarded/skimmed afterwards. Upstairs we had to install the engineered oak flooring after the plastering due to the risks of damage to the floor (general mess plus high moisture content due to wet plaster damaging the floor) - this means they had to leave an exact gap to allow the floor to be laid, with the floor ending up touching the bottom of the shadow gap profile. 

Hi @Trw144 can I ask how you laid the engineered flooring after you had the walls completed as I am trying to puzzle out the same thing now. . I understand the mechanics of fixing the wall board down to the correct height so that the floor then slides under and leaves the desired height of shadow gap. My query is how do you set the short board joins? The long lengths are fine as they are fully exposed other than the 10mm or so tucked under the shadow gap. But we will be using mixed lengths of 1.8 - 3m for a floor about 4m x 4m and so the boards need to be joined to get across the full 4m length? I think the standard way to do this is to use a pull bar and hammer but that means somehow getting the end of the bar under the far edge of the board which is under your plasterboard if you see what I mean? While this might be possible at one end what about the other length that you are butting on to? How does that stay in one place as you hammer the other piece? Would it not hammer in tight under your plasterboard on the other wall and mean you have no expansion gap at that side? Maybe use 2 pull bar left and right and two people hammering at the same time?

[Tetrarch]

I specified shadow gaps in our refurb but actually moved away from the idea for a couple of reasons:

 

• Effectively "removing" the layer of plasterboard would expose the steel frame and void that would compromise the internal insulation and make airthightedness more difficult to achieve.
• Good though my plasterer was, shadow gaps are extremely difficult to get perfect and any discrepancy would stick out (as previously noted) 
• Getting a really good intersection around door frames would be a challenge and would likely place for cracking in the future

I went with a "shadow gap" architrave, which I am satisfied with, the bonus is that using the same profile with thicker architrave made decorating exceptionally easy

 

 

 

 

 

Regards

 

Tet

[Trw144]

On 27/01/2025 at 19:11, markharro said:

Hi @Trw144 can I ask how you laid the engineered flooring after you had the walls completed as I am trying to puzzle out the same thing now. . I understand the mechanics of fixing the wall board down to the correct height so that the floor then slides under and leaves the desired height of shadow gap. My query is how do you set the short board joins? The long lengths are fine as they are fully exposed other than the 10mm or so tucked under the shadow gap. But we will be using mixed lengths of 1.8 - 3m for a floor about 4m x 4m and so the boards need to be joined to get across the full 4m length? I think the standard way to do this is to use a pull bar and hammer but that means somehow getting the end of the bar under the far edge of the board which is under your plasterboard if you see what I mean? While this might be possible at one end what about the other length that you are butting on to? How does that stay in one place as you hammer the other piece? Would it not hammer in tight under your plasterboard on the other wall and mean you have no expansion gap at that side? Maybe use 2 pull bar left and right and two people hammering at the same time?

I'm afraid I don't remember quite how they did it. If I was to guess I would say there was more space under the shadows gap that allowed them to go further in, and then pull back into the tongue. Either that or we did away the tongues as it's all glued down. Sorry I can't be of more help.