How to insulate this wall?

I have a mudroom which in a winter time is very cold. There are couple of issues that contribute to this. Underneath the mudroom is a crawl space which has just joists and fiberglass between them. There is one vent that is currently closed with a piece of green insulation (shown on photos) as I have tried to prevent cold air from accessing the crawl space from the outside (the sliding vent cover is not sealing enough when closed). Another issue is that the walls are thin and they just feel cold to the touch. There is fiberglass between studs underneath sheetrock. Without ripping walls on the inside to replace the fiberglass with better insulation, can you guys think of any way to insulate the mudroom from the outside?

 

Is there an HVAC vent in the room? if not, can you add one?
Only you can say if it would be worth removing the siding and insulating on the exterior side.

 

There is baseboard heater which I just replaced with a new one but still even at 4 ft it is not big enough to overcome the cold walls.

What could I add to the exterior walls as an additional insulation? I do not mind removing the siding. This is a lot less messy than removing sheetrock on the inside.

 

Rigid foam is commonly used between sheathing and siding.

Is there insulation in the ceiling?

 

I can add rigid foam to the outside. I would just have to figure out the logistics of pushing the walls out couple of inches.

Not sure about the ceiling. There is no entrance to the attic. I guess it is a sealed but empty space. Looking at the rest of the house, there is most likely only fiberglass between the joists but nothing on the roof.

 

I doubt it's going to be worth the cost and effort to insulate walls if the ceiling is not.

 

I will have to check but I do not think that ceiling is as cold as floor and walls. I understand that the complete insulation would include adding more to the ceiling but since I can't get up there, I can only try to fix the walls that are accessible.

I can't add more than 1-1.5" of insulation on the outside without extending roof line (at least on one side).

 

Warm air rises. Unless you heat the floor it's always going to be colder at the floor regardless of insulation. Without insulating the ceiling, you're losing so much heat there that insulating the walls is putting a band aid on a sucking chest wound.

 

Ceilings will always seem warmer than floors in the winter but your concern is "where is the heat escaping?" If there is little insulation in the ceiling that is a big contributor.

Similar with floors. Even if well insulated they will feel cold because the warm air is pushed up to the ceiling.

The best way to start is to identify where the heat is going and decide which of those areas is within your budget to correct. Air sealing is considered a good place to start and is very DIY in most cases.

You said no access to the attic above this room, how about access to the crawlspace below. One major area of air leakage is where the building rests on the foundation. Using rigid insulation many home owners will cut and fit pieces into the rim directly above the concrete and seal it with expanding foam. The cut, fit, seal, approach can continue over the top edge of the concrete and down below grade height. The result would be no cold air entering the crawlspace and greatly reduced heat loss, thus warmer floors for the room above.

While down there you can also seal around any wiring holes or other holes to improve the walls above.

That's a start.

Bud