[godblsmnymkr]

hey there.
so i bought a 30 year old house last year in BC Canada. its on an island and never gets much lower then 23f and never hotter then 90. the house foundation is built directly onto the bedrock. the previous owner built the house allowing for rain water run off to run through the basement. it enters in a bunch of different spots and exits out a drain pipe. pretty neat to listen to running water in your basement but def a humidity issue down there.

now here is the problem: rats. so between the ceiling joists is Pink Batts. then on the COLD side of the insulation they put in a poly vapor barrier (thats incorrect right? you want to have the barrier on the warm side. so would i want to replace it with faced insulation facing up the ceiling?) the rats have gotten into the insulation and ruined it in many places and it needs to come out.
my plan was to replace it with Roxul R14, but doing some reading it seems like maybe insulating ceiling of unheated basement is not worth it because of pipes and ducts getting in the way of a proper seal. one article i read was to just insulate the walls and leave the ceiling alone. this concerns me though because of the running water. I'm in way over my head here and need some advice.
thanks!
aaron

 

[godblsmnymkr]

i forgot to add: the living area is directly above this unheated basement with hardwood floors. it gets pretty cold in the house which may be a function of older windows but also the messed up insulation that is currently below the floor in the ceiling of the basement.

 

[Windows on Wash]

Treat is like a crawlspace in this case. Use a combination of rigid foam and a proper vapor control layer (can be incorporated into the rigid foam) to insulate the joists and effectively move them into the conditioned space.

I would cover the entirety of everything with something that the rats can't get behind like a thin plywood or similar building material.

http://buildingscience.com/documents/insights/bsi-009-new-light-in-crawlspaces

 

[GottaFixIt]

What is the basement floor made of?

Sounds like a dirt/rock floor, but you have water running across it?

The ideal "encapsulation" method (sealing off the outside and treating the entire inside as conditioned space) would still require water mitigation (you don't want standing water trapped under a vapor barrier) and won't fix the rat problem.

I think Windows on Wash is pointing you towards [Figure 7: Cavity Insulation with Vapor Barrier] on his buildingscience link. I believe that the best choice in your situation.

I don't know about rats, but we deal with mice a lot around here. They're almost impossible to keep out of anything that they want to get through including plywood. I think you may need to treat your rodent problem as a separate issue rather than trying to block them from the insulation, but a layer of tight wire welded fence may work to keep them out.

 

[godblsmnymkr]

What is the basement floor made of?

Sounds like a dirt/rock floor, but you have water running across it?

The ideal "encapsulation" method (sealing off the outside and treating the entire inside as conditioned space) would still require water mitigation (you don't want standing water trapped under a vapor barrier) and won't fix the rat problem.

I think Windows on Wash is pointing you towards [Figure 7: Cavity Insulation with Vapor Barrier] on his buildingscience link. I believe that the best choice in your situation.

I don't know about rats, but we deal with mice a lot around here. They're almost impossible to keep out of anything that they want to get through including plywood. I think you may need to treat your rodent problem as a separate issue rather than trying to block them from the insulation, but a layer of tight wire welded fence may work to keep them out.

thanks for the helpful reply guys.
that hardware cloth is exactly what i was planning on using. try to seal off all the areas between the joists that i can, put hardware cloth on different ends of the joists to encapsulate certain areas of the insulation, and cover the whole basement ceiling with the hardware cloth overtop of the insulation. it will be a ton of work but hopefully worth it as it should keep the rats out of most areas, thus keeping the integrity of the Roxul insulation intact.
the floor of the basement is bedrock with different levels. looks kinda like a mini mountain range. my dad was saying because the floor is exposed rock with not thermal resistance is why they put vapor barrier on cold side of insulation.

i'm also thinking of getting an energy audit done on my house and in turn asking them what they think is best for the basement. there are grants i can apply for through the power company that would basically pay for the job.

so here's my basic strategy and tell me if you see any flaws with it.
rip out old soiled fiberglass batts. install Roxul 14 between the joists. cover with hardware cloth. seal with vapor barrier.
thanks for the advice guys its appreciated.

 

[GottaFixIt]

so here's my basic strategy and tell me if you see any flaws with it.
rip out old soiled fiberglass batts. install Roxul 14 between the joists. cover with hardware cloth. seal with vapor barrier.
thanks for the advice guys its appreciated.

I think you should re-look at that link from Bud. The key to this system is encapsulating the joists/floor assembly in order to isolate from the cold side. The un-interrupted layer of foam board below the joists is the heart of the system. This means the joists themselves are warm, conditioned and protected from moisture.

In your case, that would probably mean rockwool in the bays, a layer of 2" foil faced polyiso(covers the vapor barrier), and probably some furring strips screwed through the foam into the joists to give you something to nail your cage to.

Make sure you don't have a vapor barrier somewhere in the floor assembly. You definitely don't want both. This can include vinyl flooring.

 

[Windows on Wash]

I think you should re-look at that link from Bud. The key to this system is encapsulating the joists/floor assembly in order to isolate from the cold side. The un-interrupted layer of foam board below the joists is the heart of the system. This means the joists themselves are warm, conditioned and protected from moisture.

In your case, that would probably mean rockwool in the bays, a layer of 2" foil faced polyiso(covers the vapor barrier), and probably some furring strips screwed through the foam into the joists to give you something to nail your cage to.

Make sure you don't have a vapor barrier somewhere in the floor assembly. You definitely don't want both. This can include vinyl flooring.

Who the heck is Bud...? :biggrin2:

 

[godblsmnymkr]

I think you should re-look at that link from Bud. The key to this system is encapsulating the joists/floor assembly in order to isolate from the cold side. The un-interrupted layer of foam board below the joists is the heart of the system. This means the joists themselves are warm, conditioned and protected from moisture.

In your case, that would probably mean rockwool in the bays, a layer of 2" foil faced polyiso(covers the vapor barrier), and probably some furring strips screwed through the foam into the joists to give you something to nail your cage to.

Make sure you don't have a vapor barrier somewhere in the floor assembly. You definitely don't want both. This can include vinyl flooring.

ok i re read it and understand the link. I'm not sure if putting polyiso on the cold side of the joists to protect them is worth it?
1) there are pipes and heating ducts everywhere. it would be a nightmare cutting to fit everything around all the obstacles.
2)i've noticed no mold or rot on the joists. i havent taken down the all the insulation yet so there might be some but so far havent seen anything. keep in mind this house is decades old.
3) would probably make more sense to just spray foam the ceiling instead of some elaborate mix of different types of insulation, vapor barriers and hardware cloth. it would probably only cost a little more but the time and hassle it would save might be huge.
would spray foam be a viable solution for the ceiling to keep the upstairs warm and protect the ceiling from moisture?

i got quoted at $6000 to spray foam the ceiling, but that was for R28. if i halfed that it might be more economical.
thanks for the help guys. I'm in over my head and i appreciate the help!

 

[Windows on Wash]

If there is a bunch of mechanical and water lines, you can't insulate the floor as referenced for reasons other than difficulty. If you insulate the floor as the link I referenced does, you will create other issues like pipes freezing.

You only have two options really and they are to insulated and condition the basement or insulate the floor.

Well...option 3 is to leave it as is, but you still have the rodent issue.

Maybe some pictures will help folks visualize what you have going on.

 

[godblsmnymkr]

sure
heres a pic of the way the insulation is now with the vapor barrier ripped down
this is a more heavily congested area of the ceiling

heres a pic of a spot where i started to put the ROXUL in to replace the old insulation.
thats a pipe in the backround where water from the outside comes in from.

this is a pick of what the "floor" in the basement looks like. mountainous terrain with water coming in

another pick of a more typical area of the ceiling

now to be clear, I havent found any rot or mold on the ceiling. this house is decades old. does that mean no rot will occur or just a matter of time the way the insulation is done currently. i just have a hard time believing that after 30 years there is no rot, that rot could happen and therefore i need to condition the area of the joists.
the coldest it gets is approx 21 Fahrenheit. therefore the basement would be warmer then that. maybe its not cold enough for the joists to rot?
thanks for the advice guys

 

[GottaFixIt]

Who the heck is Bud...? :biggrin2:

So sorry, got confused between two threads. Besides, Windows on Washington is way too long anyway. Do you have a preferred abbreviation?

 

[GottaFixIt]

this is a pick of what the "floor" in the basement looks like. mountainous terrain with water coming in

That is the coolest crawlspace I've ever seen Everything really is in amazingly good condition considering the water in there. Maybe between the flora and fauna in there, it's created a self regulating eco-system and you don't need to do anything, lol

A cold side vapor barrier can be viable, but not with insulation that allows air movement by convection, which unfortunately, includes rockwool and other "soft" insulations. Well, at least not without the uninterrupted convection break that the foam board provides in the building science article.

You are in a very difficult situation and I think investing on a closed cell spray foam may be your only good solution.

 

[lenaitch]

That's quite an ecosystem down there. I'm surprised at the green plant live thriving in the dark.

"Do you have a preferred abbreviation?"

I think WoW is appropriate.

 

[Nik333]

"Do you have a preferred abbreviation?"

I think WoW is appropriate.

Win is pretty good, too :}

 

[Windows on Wash]

So sorry, got confused between two threads. Besides, Windows on Washington is way too long anyway. Do you have a preferred abbreviation?

WoW works like said below.

That is the coolest crawlspace I've ever seen Everything really is in amazingly good condition considering the water in there. Maybe between the flora and fauna in there, it's created a self regulating eco-system and you don't need to do anything

I agree with you. Crazy that this system is working.

With all the mechanical and other stuff in there, the only think I can see to do is to frame the bottom of the joists down (i.e. scab in some lumber to create a new lower elevation) and then more easily insulated that lower surface. Otherwise you have so much stuff hanging down and around that it would take forever to get it all button up and some stuff would be outside the thermal boundary.

 

[Nik333]

WoW might be hard for some men to say :laugh:

 

[godblsmnymkr]

thanks for all the replies guys.
actually, those are fake plants down there left from the previous owners so thats where the confusion comes from lol.

finally got to talk to my dad more about the situation. he said just to rigid board insulate the foundation walls, ripout all the old bad insulation from the ceiling, spray it with deck treatment to protect it from the moisture and thats it.
makes a lot of sense to me and will be far easier then the plan that i had.
only problem is its going to be a serious PITA to try to cut the bottom of the rigid board to fit the always different elevations of the ground.
I guess the plan there would be to cut the bottom of the board to match the ground the best i could, then spray great stuff to fill in the cracks between the floor and the board where the cut wasnt perfect...
or spray foam insulate all the walls instead.
what do you guys think of this? what R value should I use for the walls? it would condition the basement and i think its a pretty good plan.
thanks

 

[godblsmnymkr]

after doing a little big of research, Dow Thermax seems best to use in my situation. big problem i see though is the fact that water comes into the house through the foundation in a ton of different spots where the foundation meets the rock floor. not really sure what the solution would be in those spots...
just dont put anything there?

 

[Windows on Wash]

I don't like insulating that wall and conditioning that space to be honest. How are you going to handle the moisture in the air via the water coming through the wall?

 

[godblsmnymkr]

spray the wood ceiling with water proofing deck treatment. the rigid foam is water resistant right?
i contacted a well reviewed insulation company to see what they thought would be the best solution.