Replacing a light embedded in Hardie...

[BK777]

We had our house re-sided a couple years ago. They did a pretty good job but cut a few corners. I think this is one of them. It looks like, rather than removing this light & flashing around it, they just cut a hole for it and caulked if afterwards. I can't believe I didn't notice this when we were doing final walkthroughs.



In any case, I'm looking to replace this light now. I'm pretty sure, once I cut the caulk and remove it, I'll see a hole with the old siding behind it. So I'm sure I'll be able to slide things behind it. The new light is a similar design, but slightly smaller.



What would be the ideal way to flash this? I know they make blocks for this kind of thing but it looks like they were intended to go under the siding at the time of installation. I don't want to remove any siding if I can help it. There's a small chance I'll be able to take the front half off, leaving the base attached & just attach the new light to the old base. But I won't know until I take it apart. It's hard to tell from the pic but the new light should fit inside the base area.



This side of the house is exposed to everything. Lots of sun & lots of rain.

 

[Copymutt]

I’d cut out an oversized base plate/trim and caulk it well. Should be large enough to cover the hole and contain a caulk bead w/o showing.

 

[850xpeps]

Get a piece of hardie trim that’s wide enough to cover the hole. Cut it long enough and then cut the hole in siding for the trim to slip inside. Caulk the edges. Obviously dril hole for electrical wire to come out. And buy yourself the proper color match caulk from hardie. Translucent or clear looks terrible. Like they didn’t care.

 

[BK777]

I know the siders didn't always use matching caulk. But we had the house painted with 2 coats of Superpaint and it looks pretty good. But here because it wasn't a neat boundary, the painter probably taped it and it just doesn't look great up close.

So I think one of you is saying cover the hole with a slightly bigger piece of trim and the other is saying to fit the trim inside the hole. The 2nd option sounds better to me given that I could also probably fit some head flashing over that, then the sides would be the weak point.

I hate relying on caulk as the sole means of waterproofing. But I'll feel better if I can get something protecting the top of the hole. I was hoping there was some product that could slip behind the siding, perhaps in sections. I'm sure this kind of situation is relatively common but I don't have a lot of experience with siding/flashing/waterproofing exteriors.

 

[driftpin]

What about routing a channel on the backside of the new Hardi-Board piece, of whatever size you choose to use, fill it with caulk so there is a bit of the bead 'proud' of the back, and place that?

I suppose you could cut a U-shape piece of L-angle flashing and insert it behind the Hardi-Board if you wanted.

 

[850xpeps]

I know the siders didn't always use matching caulk. But we had the house painted with 2 coats of Superpaint and it looks pretty good. But here because it wasn't a neat boundary, the painter probably taped it and it just doesn't look great up close.



So I think one of you is saying cover the hole with a slightly bigger piece of trim and the other is saying to fit the trim inside the hole. The 2nd option sounds better to me given that I could also probably fit some head flashing over that, then the sides would be the weak point.



I hate relying on caulk as the sole means of waterproofing. But I'll feel better if I can get something protecting the top of the hole. I was hoping there was some product that could slip behind the siding, perhaps in sections. I'm sure this kind of situation is relatively common but I don't have a lot of experience with siding/flashing/waterproofing exteriors.

How close is your light to the soffit above? Common practice with hardie is to caulk boards to the trim. No special flashing.

Yes I am suggesting fitting the trim inside. The trim will be 1” thick so will protrude. Just like the light base now does. Caulk the edges and top of it. Window installations rely on caulk as do roofing ones. I prefer not to when I can but it’s sometimes a failsafe. Your siding should be overtop a moisture barrier anyway that should deflect any water that gets passed out and away.

 

[BK777]

How close is your light to the soffit above? Common practice with hardie is to caulk boards to the trim. No special flashing.

It's about 12". The soffit is almost non existent. Any slant to the rain and this gets wet. But it's not 100% of the time.

Yes I am suggesting fitting the trim inside. The trim will be 1” thick so will protrude. Just like the light base now does. Caulk the edges and top of it. Window installations rely on caulk as do roofing ones. I prefer not to when I can but it’s sometimes a failsafe. Your siding should be overtop a moisture barrier anyway that should deflect any water that gets passed out and away.

This makes sense. There is a moisture barrier underneath -- I'll have to try not to cut it.

I think I have a plan, it just sounds like more of a pain than I originally thought. Thanks for the advice.

By the way, this is what I was thinking of when I mentioned head flashing. This is how the siding guys wrapped the light on the other side of the house. Well under a porch. In a place that will never ever get wet...

 

[Jim_No_Garage]

The soffit is almost non existent. Any slant to the rain and this gets wet. But it's not 100% of the time.

<snip>

This is how the siding guys wrapped the light on the other side of the house. Well under a porch. In a place that will never ever get wet...

It's like when the sheetrockers glue and screw the closet ceiling but not the bedroom ceiling.

I never considered that Hardie would be more difficult to make changes like replacing lights and such.

Cheers

Jim

 

[Falcon67]

I have lights mounted to the HardiPanel on my shop, I only caulked the hole where the wire exited. They are up on the wall and semi-protected by the eve. I have pieces of Hardi that have been laying on the ground behind the shop since 2011 that haven't fallen apart, so a little splash that might get behind a fixture up on a wall is nothing IMHO.

I put this up in 2012 with just a bit of caulk in the exit hole, no issues. The pipe flange it screwed to a backer under the siding, with no fugly caulk around it.

 

[CraigStu]

You haven't removed the old light yet so seem to be guessing what is under it.

 

[bradpac]

Cut yourself a block that fits that hole in the siding. Drill a hole in it for the wire and secure it in place with some sealant and mount the light on top of the block.

 

[TLCObsession]

By the way, this is what I was thinking of when I mentioned head flashing. This is how the siding guys wrapped the light on the other side of the house. Well under a porch. In a place that will never ever get wet...

The head flashing should be as shown but the part under the siding should extend an inch to either side of the opening under the Hardie