Long post follows.....


I've got a problem with condensation in my workshop I can't understand.

I'm getting condensation on the bottom side of the metal beam above the
doorway. It extends about 1 foot to the left of the door. The other roof
beams stay dry, it only appears to condense above the door and a little
to each side of the door.


https://dl.dropboxusercontent.com/u/...tion%20(1).JPG

https://dl.dropboxusercontent.com/u/...tion%20(2).JPG



Initially I thought it was roof leakage so I lifted the cladding and
replaced the metal flashing angle, sealing both sides well with a
copious amount of silicone sealant.


I found the condensation was still occurring and thought that it may be
damp air drawn into the shed at night via the gap between the door and
the door frame. I figured the moisture was condensing on the cool metal
beam (the cladding is screwed to the top side of this beam) so I
purchased some neat fitting self adhesive rubber seal. I fitted this
across the top and down the sides of the door. The bottom of the door
has a wiper type storm seal.


Despite this on rainless nights / days I'm still getting
condensation drips forming on the metal beam. Where is it coming from??????


What I know:

1) Clay brick walls.
2) Steel beams 4" x 2".
3) Flat sheet steel roof cladding.
4) Temperature range - days typically 70F, nights may go as low as 40F
5) Roof lined with 2" polystyrene sheets spaced 1" from roof cladding.
6) Door / door frame gap sealed.
7) I have a "whirly bird" wind driven ventilator at the high end of the
roof opposite the door (12 feet away).
8) I added a solar panel driven 120mm 12V fan to pump outside into the
shed in an attempt to keep it dry - its made no difference in 2 weeks of
running.
9) Weather location - Perth Western Australia.



Ideas ???

Cheers.

Shed_Fiddler fired this volley in
. au:

Ideas ???

Well, start with basics. The beam itself is becoming cooler than the
dewpoint of the air.

Since that beam is close to a door, one can construe that it's close to a
wall... and perhaps _itself_ not insulated from the outside air
temperature at night.

If I were looking for the problem, I'd be looking for a thermal path to
that beam from outside. Perhaps the cladding is screwed right to the
beam? Perhaps the eaves are venting up directly across the top of that
beam (between roof and insulation sheets), and once the air has removed
the heat from that beam, it's warm enough and diffuse enough not to cool
other beams it passes on the way to the peak? Or perhaps once having
passed that beam, the air is mixed with other inside air, and thus is not
so cool anymore.

There are all sorts of ways to imagine that happening, but the simple
fact is that the one beam is getting cooled to below the dew point, while
the others are not.

LLoyd

On 8/7/2014 7:21 AM, Lloyd E. Sponenburgh wrote:
Shed_Fiddler fired this volley in
. au:

Ideas ???

Well, start with basics. The beam itself is becoming cooler than the
dewpoint of the air.

Since that beam is close to a door, one can construe that it's close to a
wall... and perhaps _itself_ not insulated from the outside air
temperature at night.

If I were looking for the problem, I'd be looking for a thermal path to
that beam from outside. Perhaps the cladding is screwed right to the
beam? Perhaps the eaves are venting up directly across the top of that
beam (between roof and insulation sheets), and once the air has removed
the heat from that beam, it's warm enough and diffuse enough not to cool
other beams it passes on the way to the peak? Or perhaps once having
passed that beam, the air is mixed with other inside air, and thus is not
so cool anymore.

There are all sorts of ways to imagine that happening, but the simple
fact is that the one beam is getting cooled to below the dew point, while
the others are not.

LLoyd


Spray an inch or two of foam insulation over the beam.
Air can't get to the beam to condense, and the foam will stay
warm enough so no water will condense on it.

I don't know if you can do that with the little foam
bottles you buy at Lowes, you need it to come out in a
spray so it seals all inflow of air to the beam.

Mikek

amdx fired this volley in news:lrvt6o$hop$1@dont-
email.me:

I don't know if you can do that with the little foam
bottles you buy at Lowes, you need it to come out in a
spray so it seals all inflow of air to the beam.

There are foam ball-filled paints that offer the same feature in a
rolled-on application. One could even 'dope up' a can of latex paint
with a beanbag full of polybeads, and just spatula the stuff on. In
fact, I've seen and once used a pre-mix version of that, though I cannot
remember where I got it. It's the consistency of spackle, and about 90%
polybeads.

Or you could 'baggie' the beam, and fill it with some low-expansion (door
and window) foam.

Lloyd

On 8/7/2014 8:06 AM, Lloyd E. Sponenburgh wrote:
amdx fired this volley in news:lrvt6o$hop$1@dont-
email.me:

I don't know if you can do that with the little foam
bottles you buy at Lowes, you need it to come out in a
spray so it seals all inflow of air to the beam.

There are foam ball-filled paints that offer the same feature in a
rolled-on application. One could even 'dope up' a can of latex paint
with a beanbag full of polybeads, and just spatula the stuff on. In
fact, I've seen and once used a pre-mix version of that, though I cannot
remember where I got it. It's the consistency of spackle, and about 90%
polybeads.

Or you could 'baggie' the beam, and fill it with some low-expansion (door
and window) foam.

Lloyd


That's what I was trying to convey, the door and window foam.
I wonder how it would come out of you pinched or restricted the tube
on one of the door and window foam cans? Could you get a spray?

Mikek

amdx fired this volley in news:lrvtv1$nfg$1@dont-
email.me:

That's what I was trying to convey, the door and window foam.
I wonder how it would come out of you pinched or restricted the tube
on one of the door and window foam cans? Could you get a spray?

No, not a useful one. 'Boxing' the beam with some light framing, then
filling the void end-to-end would be the easiest way with that material.
You could even use a piece of plastic gutter material as the trough.

All that said, it would prevent the drip, but not expose the underlying
cause. I'm prone to 'waste' the time it would take to understand it
before I worked around the problem. It might not be soluble without
extensive structural changes. Then the foam would be the ideal solution.

But it also might be as simple as pulling out a few screws, sliding in a
thermal barrier between roof and beam, and putting the screws back in.

LLoyd

"Shed_Fiddler" wrote in message
. au...
Long post follows.....


I've got a problem with condensation in my workshop I can't
understand.

I'm getting condensation on the bottom side of the metal beam above
the doorway. It extends about 1 foot to the left of the door. The
other roof beams stay dry, it only appears to condense above the
door and a little to each side of the door.


https://dl.dropboxusercontent.com/u/...tion%20(1).JPG

https://dl.dropboxusercontent.com/u/...tion%20(2).JPG



Initially I thought it was roof leakage so I lifted the cladding and
replaced the metal flashing angle, sealing both sides well with a
copious amount of silicone sealant.


I found the condensation was still occurring and thought that it may
be damp air drawn into the shed at night via the gap between the
door and the door frame. I figured the moisture was condensing on
the cool metal beam (the cladding is screwed to the top side of this
beam) so I purchased some neat fitting self adhesive rubber seal. I
fitted this across the top and down the sides of the door. The
bottom of the door has a wiper type storm seal.


Despite this on rainless nights / days I'm still getting
condensation drips forming on the metal beam. Where is it coming
from??????


What I know:

1) Clay brick walls.
2) Steel beams 4" x 2".
3) Flat sheet steel roof cladding.
4) Temperature range - days typically 70F, nights may go as low as
40F
5) Roof lined with 2" polystyrene sheets spaced 1" from roof
cladding.
6) Door / door frame gap sealed.
7) I have a "whirly bird" wind driven ventilator at the high end of
the roof opposite the door (12 feet away).
8) I added a solar panel driven 120mm 12V fan to pump outside into
the shed in an attempt to keep it dry - its made no difference in 2
weeks of running.
9) Weather location - Perth Western Australia.



Ideas ???

Cheers.

A simple way to investigate air infiltration is to ballast a Mylar
helium balloon to neutral buoyancy and watch where it travels. Latex
balloons work but leak down fast enough that you'll have to adjust the
weight frequently. I used thread and snipped the end. Watch out for
heaters and exposed light bulbs.
-jsw

On 07-Aug-14 9:28 PM, Lloyd E. Sponenburgh wrote:
amdx fired this volley in news:lrvtv1$nfg$1@dont-
email.me:

That's what I was trying to convey, the door and window foam.
I wonder how it would come out of you pinched or restricted the tube
on one of the door and window foam cans? Could you get a spray?

No, not a useful one. 'Boxing' the beam with some light framing, then
filling the void end-to-end would be the easiest way with that material.
You could even use a piece of plastic gutter material as the trough.

All that said, it would prevent the drip, but not expose the underlying
cause. I'm prone to 'waste' the time it would take to understand it
before I worked around the problem. It might not be soluble without
extensive structural changes. Then the foam would be the ideal solution.

But it also might be as simple as pulling out a few screws, sliding in a
thermal barrier between roof and beam, and putting the screws back in.

LLoyd



Thanks for the ideas guys.

I like the idea of insulating the beam surface. I may be able to find
some thin self adhesive insulation - cheap & effective.

The thermal barrier idea is interesting but will be difficult as I
initially thought is was water leakage (its winter here) and I've pretty
much glued the cladding to the beam with silicone rubber (silastic). The
thing I don't get is that the beam is the full length of the workshop
and it only gets condensation over the top of the door frame. Everything
else is equal - that's why I figured it was from air leakage around the
door.

I'll head to our big hardware retailer and see what insulation they have.

Cheers.

On 07-Aug-14 11:11 PM, Jim Wilkins wrote:
"Shed_Fiddler" wrote in message
. au...
Long post follows.....


I've got a problem with condensation in my workshop I can't
understand.

I'm getting condensation on the bottom side of the metal beam above
the doorway. It extends about 1 foot to the left of the door. The
other roof beams stay dry, it only appears to condense above the
door and a little to each side of the door.


https://dl.dropboxusercontent.com/u/...tion%20(1).JPG

https://dl.dropboxusercontent.com/u/...tion%20(2).JPG



Initially I thought it was roof leakage so I lifted the cladding and
replaced the metal flashing angle, sealing both sides well with a
copious amount of silicone sealant.


I found the condensation was still occurring and thought that it may
be damp air drawn into the shed at night via the gap between the
door and the door frame. I figured the moisture was condensing on
the cool metal beam (the cladding is screwed to the top side of this
beam) so I purchased some neat fitting self adhesive rubber seal. I
fitted this across the top and down the sides of the door. The
bottom of the door has a wiper type storm seal.


Despite this on rainless nights / days I'm still getting
condensation drips forming on the metal beam. Where is it coming
from??????


What I know:

1) Clay brick walls.
2) Steel beams 4" x 2".
3) Flat sheet steel roof cladding.
4) Temperature range - days typically 70F, nights may go as low as
40F
5) Roof lined with 2" polystyrene sheets spaced 1" from roof
cladding.
6) Door / door frame gap sealed.
7) I have a "whirly bird" wind driven ventilator at the high end of
the roof opposite the door (12 feet away).
8) I added a solar panel driven 120mm 12V fan to pump outside into
the shed in an attempt to keep it dry - its made no difference in 2
weeks of running.
9) Weather location - Perth Western Australia.



Ideas ???

Cheers.

A simple way to investigate air infiltration is to ballast a Mylar
helium balloon to neutral buoyancy and watch where it travels. Latex
balloons work but leak down fast enough that you'll have to adjust the
weight frequently. I used thread and snipped the end. Watch out for
heaters and exposed light bulbs.
-jsw




Good thought Jim, helium might be a bit of a pain, but I may go out
there this evening and hold a candle near the door and see if I can spot
any draft around its perimeter.

On 8/8/2014 2:39 AM, Shed_Fiddler wrote:
...
I like the idea of insulating the beam surface. I may be able to find
some thin self adhesive insulation - cheap & effective.
...

Don't get it so thin that it doesn't insulate enough and you just get
condensation on the insulation.

On 8/8/2014 7:15 PM, Bob Engelhardt wrote:
On 8/8/2014 2:39 AM, Shed_Fiddler wrote:
...
I like the idea of insulating the beam surface. I may be able to find
some thin self adhesive insulation - cheap & effective.
...

Don't get it so thin that it doesn't insulate enough and you just get
condensation on the insulation.


Also, make sure you seal it well so no air can circulate, otherwise
the insulation you have installed keeps the beam from warming and the
air that does circulate, has the water condense out on the beam.

On Thursday, August 7, 2014 3:59:43 AM UTC-7, Shed_Fiddler wrote:

I've got a problem with condensation in my workshop I can't understand.


I'm getting condensation on the bottom side of the metal beam above the
doorway. It extends about 1 foot to the left of the door. The other roof
beams stay dry...

I'll offer a contrarian view: your condensation results from cold iron
and moist air. Since moisture is NOT a good thing, put MORE cold iron
up there (I'm thinking a galvanized pipe with water fill, lotsa pounds per foot)
and pitch it so the condensation collects at a drain or drains. If you see
beads form, apply wetting agent (or some of that sheeting-action auto
finish) so the water flows to the drain. I like 'amdx' suggestion to foam
insulate the beam (so it doesn't rust).

On 13-Aug-14 3:47 AM, whit3rd wrote:
On Thursday, August 7, 2014 3:59:43 AM UTC-7, Shed_Fiddler wrote:

I've got a problem with condensation in my workshop I can't understand.


I'm getting condensation on the bottom side of the metal beam above the
doorway. It extends about 1 foot to the left of the door. The other roof
beams stay dry...

I'll offer a contrarian view: your condensation results from cold iron
and moist air. Since moisture is NOT a good thing, put MORE cold iron
up there (I'm thinking a galvanized pipe with water fill, lotsa pounds per foot)
and pitch it so the condensation collects at a drain or drains. If you see
beads form, apply wetting agent (or some of that sheeting-action auto
finish) so the water flows to the drain. I like 'amdx' suggestion to foam
insulate the beam (so it doesn't rust).



That's an interesting idea, unfortunately not really practical to do in
my shed though. When I get a chance I'm going to get some insulation and
cover the part of the beam that's giving me trouble. Next summer I'll
put some more sealant on the outside of the single layer brick wall to
try to further reduce moisture ingress.

Cheers.

On Wednesday, August 13, 2014 9:15:21 AM UTC-4, Shed_Fiddler wrote:
On 13-Aug-14 3:47 AM, whit3rd wrote:

On Thursday, August 7, 2014 3:59:43 AM UTC-7, Shed_Fiddler wrote:

I've got a problem with condensation in my workshop I can't understand.

I'm getting condensation on the bottom side of the metal beam above the

doorway. It extends about 1 foot to the left of the door. The other roof

beams stay dry...

I'll offer a contrarian view: your condensation results from cold iron

and moist air. Since moisture is NOT a good thing, put MORE cold iron

up there (I'm thinking a galvanized pipe with water fill, lotsa pounds per foot)

and pitch it so the condensation collects at a drain or drains. If you see

beads form, apply wetting agent (or some of that sheeting-action auto

finish) so the water flows to the drain. I like 'amdx' suggestion to foam

insulate the beam (so it doesn't rust).

That's an interesting idea, unfortunately not really practical to do in

my shed though. When I get a chance I'm going to get some insulation and

cover the part of the beam that's giving me trouble. Next summer I'll

put some more sealant on the outside of the single layer brick wall to

try to further reduce moisture ingress.

For a birds-eye view, since the early 1990's, this topic has come up over and over.

Usually, the indoor humidity threads end with deciding to increasing circulation in that area (sometimes with adding and running a window-air-conditioner away from the window and put where the most condensation is collecting).

On Thursday, August 7, 2014 6:59:43 AM UTC-4, Shed_Fiddler wrote:
Long post follows.....





I've got a problem with condensation in my workshop I can't understand.



I'm getting condensation on the bottom side of the metal beam above the

doorway. It extends about 1 foot to the left of the door. The other roof

beams stay dry, it only appears to condense above the door and a little

to each side of the door.





https://dl.dropboxusercontent.com/u/...tion%20(1).JPG



https://dl.dropboxusercontent.com/u/...tion%20(2).JPG







Initially I thought it was roof leakage so I lifted the cladding and

replaced the metal flashing angle, sealing both sides well with a

copious amount of silicone sealant.





I found the condensation was still occurring and thought that it may be

damp air drawn into the shed at night via the gap between the door and

the door frame. I figured the moisture was condensing on the cool metal

beam (the cladding is screwed to the top side of this beam) so I

purchased some neat fitting self adhesive rubber seal. I fitted this

across the top and down the sides of the door. The bottom of the door

has a wiper type storm seal.





Despite this on rainless nights / days I'm still getting

condensation drips forming on the metal beam. Where is it coming from??????





What I know:



1) Clay brick walls.

2) Steel beams 4" x 2".

3) Flat sheet steel roof cladding.

4) Temperature range - days typically 70F, nights may go as low as 40F

5) Roof lined with 2" polystyrene sheets spaced 1" from roof cladding.

6) Door / door frame gap sealed.

7) I have a "whirly bird" wind driven ventilator at the high end of the

roof opposite the door (12 feet away).

8) I added a solar panel driven 120mm 12V fan to pump outside into the

shed in an attempt to keep it dry - its made no difference in 2 weeks of

running.

9) Weather location - Perth Western Australia.

Ideas ???

For a birds-eye view, since the early 1990's, this topic has come up over and over.

Usually, the indoor humidity threads end with deciding to increase circulation in the wet area (sometimes with adding and running a window-air-conditioner away from the window and put where the most condensation is collecting).