Thought I would share some experience I have had in the past, and some preventative measures you can take assuming that you haven't already.

My box is constructed mainly of 3/4" WPB ply and originally coated with a polyester gel coat to give it A) Texture and B) weather protection (well, if it works for boats and all that!)

Anyway, assuming all was well, I didn't bother periodically checking the box over. About 18-months later, I found that the roof, signs (and boxes), doors and windows were shot to pieces. The base and one wall sustained terrible damage too.

What had happened after dismantling the box became very apparent.

Roof - Gelcoat cracks with temperature changes allowed water to get into all joins. New roof.

Corner posts swelled up and warped - new corner posts required.

Fibreglass window frames had twisted out of shape with terrific heat build up in box (due to not venting the box), causing slicone seals to fail that were holding the glass in place. I had to fabricate one new side panel as water had seeped in causing rot and excess warping.

New sign boxes constructed due to rot from roof and vinyl graphics letting water in. Signs were not originally backlit.

I had a metal frame constructed to straighten the very warped left hand door as water had crept in behind the vinyl (non backlit) phone panel graphic, and through the screw holes for pull to open sign handle. This is now no longer an opening door and bolted right through. All light switches are now on the rear of this fixed door, so no great problem.

Opening door - water had crept in through the screw holes of the handle, through the lock barrel hole (these locks do let in water as they have no cover) and the window frame as above. New door frame and panel cover required due to excessive warping.

Although the box was treated with a high-end preserver covering every millimetre prior to construction and assembly, this clearly failed.

My advice from my expensive and time consuming experience would be to tend to the following...



PREVENTATIVE MEASURES

Do not use any form of gelcoat - the thicker you apply, the more brittle it becomes. Also, there is very little movement with this, so expansion and contraction WILL crack it allowing water to get to the wood.

Do not use any form of silicone sealant. If you can, use a product such as Sikaflex 227 to join the box, caulk joints and fix glass in place. It can also be overpainted and will not fail.

Use a product such as Isoflex liquid rubber internally as well as externally - yes, it is expensive, but can be the difference between a box lasting many years, or one deteriorating rapidly. Pay attention to all edges prior to assembly, just in case any water gets into a joint. It cannot do any harm if it does. Also, ALWAYS use the Isoflex primer first. This gives a sort of chemical reaction with the rubber final coat, and bonds like  

Without the special primer, there is the chance the rubber coating won't take and starts peeling/bubbling in places.

You WILL experience some form of condensation (even with venting) inside. If everything is coated in rubber, it cannot do any harm or cause mould.

Seal everything - before you install your lock barrel, use liquid rubber or Sikaflex to line the barrel hole. Water does get in there, and will cause swelling, warping of the door and decay. These locks have no cover plate, so water will get into the lock via the key hole. Same with the handles - seal them, seal the screw holes before putting the screws in as water will travel down the screw thread into the doors causing swelling, warping and decay.

Think about installing a rubber seal around the entire door. I have now done this, so when I shut it, it is a bit like a car door in as much as you have to slam it. But as a "Brucie Bonus" - it does have a 'Germanic thunk' when you do...sort of Audiish , but water will not get in.

For those of you with inwardly opening doors, invest in a rubber draught strip to mount on the lower rear of the door. It's like a wiper blade, but I guarantee that if istalled correctly, water will not creep inside from underneath the door.

Ventilation - this is so important, so consider that if you have taken the above steps, your TARDIS will be virtually airtight. Think about venting the base and the roof via the lamp housing. This creates airflow, so reduces the chance of condensation and terrific heat build up. You ideally want cold air in from the ground pushing out the hot air from the top.

It's gut wrenching to see so much effort destroyed by Mother Nature, and I'm sure that we all want to enjoy these boxes for many, many years.

Hope this helps  

Quote from: gemini39usa board=faq thread=784 post=15463 time=1217759579I have a question that hopefully someone will know the answer...............

I keep hearing about Isoflex Liquid Rubber. Has anyone in the States found a similar product that can be used and if so where?  I searched for this product and I believe it is only available in the UK?

Isoflex Liquid Rubber is a flexible rubber coating for roofs.  Doing a quick search on Google, I found: Liquid Rubber from Pro Guard Coatings which seems to be the same sort of thing.

Colin

I'm going to ask a newb question because i haven't yet begun my physical build let alone gotten that far along that I am working on the roof, but here goes...

has anyone considered trying to use Hardie Panels for the roof?
or infact any part where plywood would be used, either instead of or on top of.

For those unaware James Hardie manufactures a number of "siding" products for houses in the USA which are in essence concrete fibre.
While brittle and a pain in the ass to use once up is actually quite resiliant to the weather and warping...


You can start laughing now, lol.

I think that sounds like a good idea the weight on those hardy boards would be pretty heavy being concrete based.  Do they make panels wide enough where you could cut the roof sections out?  You also need to consider getting the roof up into position, if this is a build it and leave it arrangement you are ok, if you want something that can be broken down and moved then heaving a roof sheathed with concrete and fiber may be a bit taxing. 

Hardie panels are not much heavier than regular house siding... certainly lighter than some of the plywood panels out there, and yes they do make them in 8'x4' panels, with different patterns, though there are some that look plain or you could even flip them over as the backs are plain....

I was only thinking of it as a solution to some of the problems people seem to be having with exterior boxes.
Which for the record is what I will be building....

I am actually half considering the idea of cladding the frame with the stuff (there are panels with pronounce wood grain style patterning), it would certainly weather proof the box, I just don't know how feasible it would be

Hello,

You certainly have a tale of terror for those of us building outside boxes.

Now I don't have a complete box, but I do have parts of it that have been sitting outside for over two years so I thought I'd make a few comments.

Quote from: anotherwheeze board=faq thread=784 post=14454 time=1213825647terrific heat build up in box (due to not venting the box)

I suspect that's one of the big things that outdoor builders don't think enough about.  Having wildly different interior and exterior temperatures will create a lot of problems.

QuoteMy box is constructed mainly of 3/4" WPB ply and originally coated with a polyester gel coat to give it A) Texture and B) weather protection (well, if it works for boats and all that!)
...
Roof - Gelcoat cracks with temperature changes allowed water to get into all joins. New roof.
...
Do not use any form of gelcoat - the thicker you apply, the more brittle it becomes. Also, there is very little movement with this, so expansion and contraction WILL crack it allowing water to get to the wood.

I have a fairly thick layer of epoxy on my roof and it's been sitting outside for two years in temperatures varying from -27°C to +36°C, but I don't have any cracking.  The two big differences being firstly that since mine isn't an enclosed structure - there isn't a big difference in temperatures between top and bottom, and secondly that I've got a layer of fiberglass cloth embedded in the epoxy.  I was wondering if I were overdoing it with the fiberglass, but from your example I'm glad that I'm using it.  Resin is fairly brittle, but fiberglass cloth has a tensile strength greater than steel.  There were some places that I wasn't planning on putting down cloth, but I think I will now.

Of course, I'll have to see how it fares once my box is complete, but I have high hopes.

Do you have any pictures that you can show us of the damage?

Colin

Hi Colin,

I don't think you will have many, if any problems with your build 

Agreed, I don't think many people (myself included) realise that the temperature changes can cause such a potential problem. Venting is a must like I described above, or as Chris KingBees has done with his sign boxes. This will help control some of the expansion. Obviously, when yours is assembled you will find out (if you pardon the pun) if you have cracked it! There is a big difference between assembled, and in bits outside as you rightly pointed out.

Something else to bear in mind... different thicknesses of materials. I'll give an example - my roof is made from 1/4" WPB ply on the slopes. Although the same material as the rest of the box, it is thinner, therefore reacts differently to the thicker ply with temp changes. There is a softwood frame also, again the same problem. I was convinced that I had is sussed the first time around with the gelcoat, but I was wrong. Having said that, I used no form of reinforcement as you have.

This time around I did, but as some of the box had the gelcoat and I quite liked the texture (it sort of looks like cast iron with paint build up and runs, also crazing) I did the same again, but used the isoflex primer first to give some 'bite', then rubber x 2 coats, chopped strands etc. before painting.

Now I am happier than before, but still think I made a mistake using gelcoat again. Let me explain... me being the impatient kind primed, but applied the gelcoat to the primer whilst it was still tacky in some areas, one of them being part of the roof. Well two weeks after completing the box I noticed the damn gelcoat had cracked again. I stripped it off (the Isoflex primer was still on the wood thankfully, reprimed and used liquid rubber to cover up that area minus the gelcoat.

Now this area was in direct sunlight with the brunt of the afternoon sun beating down on this area for a number of hours. I put this down to the tacky primer as gelcoat has a wax in it to help it flow, so the two didn't bind, and also the temperature changes causing expansion and contraction. Gelcoat doesn't like this.

I have read a lot on boating stuff, and it is widely recognised that the gelcoat should be kept thin so it doesn't become brittle. Of course I have applied pretty thick in some places to achieve texture.

I think we will have to see what happens in time. We are all experimenting, and someone will have the right formula licked I'm sure. I just have a feeling that another refurb may be on the cards for my box before the year is out, but only in the places where I was impatient!

I'm just glad I don't have your extremes of temperature to deal with. I do however live in the middle of nowhere on an old converted farm, at the bottom of a "huge" hill which throws off a lot of damp in the evening, even in the summer.

My main concern for everyone would be to seal all screw holes and the lock barrel hole. My old lock was knackered with rust after only a short time.

Reminds me... grease the entire lock mechanism and a little WD40 as I have. My new yale cost a bomb, so I want it lasting as long as possible.

Unfortunately I have no photos of the damage Colin. I was too depressed to take any at that time as I just wanted to get the box fixed ASAP. I didn't take any of the refurb either as I was going through some personal problems, so just got stuck into things. I could kick myself now though for not doing it 

We may have extremes in temperature, but we don't have a lot of humidity to deal which might also help my build.

Should the gel coat go on top of primer?  I don't really know a lot about polyester resins having decided to use epoxy instead, but with the epoxy I'm putting it directly onto the raw wood (after sanding a bit to give it a rougher surface to grab onto), and then putting my paint primer on top of the epoxy.  Or are you talking about some sort of polyester resin primer?

I'm not surprised that you didn't take any pictures.  I just remember that before I started my build, I saw some pictures of someone's TARDIS that had rotted away in something like a year or two.  I don't know where I saw them or who they belonged to, but it really made me start thinking what I could do to avoid this fate.  If anyone knows where these pictures are, please let me know.

You mention WD-40.  I'd just like to point out that WD-40 is a solvent which will remove any grease that you may actually want to keep.  I know that I've been told to never use WD-40 in electrical motors for example, since it will dissolve the grease that's supposed to be inside the motor - and ruin it.  It does have lubricants, but you may want to apply other stuff to supplement them after using WD-40.

Colin (who used to think that WD-40 and duct tape could fix anything)

I have a question that hopefully someone will know the answer...............

I keep hearing about Isoflex Liquid Rubber. Has anyone in the States found a similar product that can be used and if so where?  I searched for this product and I believe it is only available in the UK?

No experience of epoxy resin myself, apart from knowing it is a tough as nails, and rather expensive. I think you should be fine.

The primer I was referring to is the Isoflex one. Once dried, nothing, but nothing shifts it. So my cunning plan was to use this and then gelcoat, rather than applying gelcoat direct to the wood as before. I just got rather impatient in some areas and proceeded to apply gelcoat before the isoflex primer had fully cured. Trouble is, I don't know how many other areas were affected Time will tell.

Should I have to do this all again, I would give the gelcoat a miss TBH.

You can get a great texture from Isoflex rubber and chopped strands. So IF I were to build another box (probably a met box after seeing KB's!) this is how I would do it with 99.9% confidence. I'm at around 75-80% confident with what I have done (was 90% before the roof cracked!)

I'm terrible for photographing things. I was too down at the damage the TARDIS suffered the frst time around, so just wanted to get on and get it done. Plus my camera is broken due to an incident with some apple juice after initially going missing...later found in a toy box! Sometimes it works, sometimes not, so have resorted to the old mobile phone camera, which isn't too clever.

I'm currently landscaping the garden - shifted around 200 tons of earth so far  Started to take photos over the first couple of days...and nothing in the last week, so the missus will 'not' be happy that we haven't a record of each stage

I just get too involved in what I'm doing I guess, so forget to take photos 

Hardie plank is what came to my mind when I began thinking about an outdoor box.
I'm just not sure if the corner edges could be mitered, and lap joint corners may look bad...
worth a test panel try for sure.
Lots of construction about to happen at my house but alas nothing TARDIS related...just an addition, sort of a guest house thing.
Oh and Happy Birthday America GO YANKS

I had not thought of Hardiplank!  It would be somewhat fitting, given that it is cement based and the original Met boxes were cast concrete.  I probably wouldn't use it for the roof, though.  My reasoning being that there would be a challenge to getting precise cuts on it and that it would be heavier and more prone to warping (I know you said it could be light as ply, just my prejudices though). 

As far as venting, a couple comments on how I did my build:  First off, my build was pretty quick, dirty, and low-budget.  It isn't screen accurate by any stretch.  And I didn't pour a concrete base to stand it on or anything like that.  I did wind up putting a brick under each corner to get it up off the ground however.  Time will tell how long it will take to drive the bricks into the earth.  For now it provides decent clearance from interaction with the soil without being distractingly "up on blocks". 

I used 4x4s for my corner posts instead of fabricating something.  If I were doing it over again, I'd use something lighter, but what are the odds that I need a second yard TARDIS?   Just wanted to mention it, from a structural standpoint.  Basically the structural elements on my TARDIS are the corner posts, the base (which is 2x4s) and the signs (which are scrap 1x12 I had laying around). 

Anyway, back to ventilation:  I didn't actually build a floor into the TARDIS.  After the structure was complete I layed a layer of plastic down (being careful that the edges were up inside the structure so water couldn't drip onto it and defeat the whole purpose) as a vapor barrier.  On top of that went a sort of "pallet" made from scrap 2x4.  Then I cut a plywood deck for the pallet that I dropped onto it.  So I have a good amount of ventilation from below. 

But I found myself increasingly worried about roof ventilation.  In efforts to waterproof a garage, I became ever more frustrated with how pervasive water is at getting into any opening, so I was really hesitant to make any openings in my structure.  But while I was reading up on the old Met boxes, I read somewhere that the lamp structure had a vent built in. 

At first this seemed counterintuitive--the very top of the roof seemed the last place you want to put a hole in your structure.  But the more I thought about it, the more it made sense.  Every place else, water runs off everything above it and has a chance to get inside.  If you make a 2" hole in the very top, raindrops that fall in that 2" area are the only ones that can get in. 

Once I cut my hole, I glued in some shims for my "lamp" to rest on.  The lamp is bigger than the vent hole, so any water would have to fall inside the housing around the lamp (more on this later) and then get blown uphill in order to drip into the TARDIS.  I also redid the housing around the lamp so it had some drain vents so if any water DID get in under the shade it could run out downhill instead of pooling up in the housing.  (And at this point I'll mention that I initially didn't have a square opening in my roof like 99% of people did, I brought the roof to a complete point and then put the (nonfunctional) lamp on top of it, outside my waterproofing.) 

Finally, I redid my lamp shade so it had a wider rim to keep water out.  When I did this I also added the top from one of those solar landscape lights so that my lamp would light up after dark.  All in all, it turned out pretty well and in spite of some particularly nasty Portland rain, the inside has stayed dry. 

All that said, my build is less than a year old.  We'll see how it holds up.  And finally, yes, the thing to remember from the original post is that maintenance is continuous.  You can't just build a TARDIS and forget about it.  You should check for any damage periodically.  The good news is, whether you are going for a TARDIS or a Met box, any repairs you make just add to the character of it.  Whether it is supposed to be an early 20th century London structure or a time machine disguised as the same, it would have some repairs and maintenance done to it over the years that would be noticeable to some degree.   

Quote from: anotherwheeze on Jun 21, 2008, 09:33 pm
The primer I was referring to is the Isoflex one. Once dried, nothing, but nothing shifts it. So my cunning plan was to use this and then gelcoat, rather than applying gelcoat direct to the wood as before. I just got rather impatient in some areas and proceeded to apply gelcoat before the isoflex primer had fully cured. Trouble is, I don't know how many other areas were affected Time will tell.

You can get a great texture from Isoflex rubber and chopped strands. So IF I were to build another box (probably a met box after seeing KB's!) this is how I would do it with 99.9% confidence. I'm at around 75-80% confident with what I have done (was 90% before the roof cracked!)

Having a quick Google for Isoflex as an option instead of fibre-glassing mine (I was going to use chopped strand or even woven cloth), I see that it only seems to come in black. Does this cause problems when putting the blue on: does it blend in with the rest or will it always be darker? I think I need some more coats on the walls anyway.

As an addendum on an ancient post:  My TARDIS has had lots of rot.  Lots.  I don't know if I've every posted a photo.  I tiled a bathroom.  I had some leftover Hardibacker from the tile work.  There are now some significant parts of my TARDIS that are done in Hardibacker. 

Quote from: alistair on Apr 17, 2018, 06:47 pm
Having a quick Google for Isoflex as an option instead of fibre-glassing... I see that it only seems to come in black. Does this cause problems when putting the blue on: does it blend in with the rest or will it always be darker?

Well, if it's paintable, you can always coat it first with the same primer you used on the rest of the box. That should take care of the color worry. Even if it takes two coats of primer to make the primer color the same as the rest of the box you'd only be adding an extra layer of protection, while at the same time making the foundation for the blue match everything else. Then when the blue goes on it should match all over the box.

I hope some of this is helpful.

Dino.