Community Forums

DougW · 06-30-2015, 04:03 PM

Dutch star with rubber membrane over plywood roof. The lag bolt holes (in the plywood) are stripped. These are the bolts used to hold down the heat pump unit and compress the gasket under each unit. It is a ducted system, so I cannot access the mounting holes from inside the coach. They are 1/2" lags, and I really don't want to up to 5/8''. Any thoughts on how to deal with this would be appreciated. Thank you, Doug

mel s · 06-30-2015, 06:39 PM

Quote:

Originally Posted by DougW

Dutch star with rubber membrane over plywood roof. The lag bolt holes (in the plywood) are stripped. These are the bolts used to hold down the heat pump unit and compress the gasket under each unit. It is a ducted system, so I cannot access the mounting holes from inside the coach. They are 1/2" lags, and I really don't want to up to 5/8''. Any thoughts on how to deal with this would be appreciated. Thank you, Doug

DougW
What make model/heat pump and what model/year Dutch Star do you have?

Most roof air/roof heat pumps are mounted with a housing on the inside of the RV.
The roof unit sits on a foam gasket/seal on the roof....the interior housing goes up against the ceiling and bolts run through that housing and thread into bottom of the roof unit.
The ceiling, attic, roof and gasket/seal are sandwiched between the inside housing and the roof unit.....and the bolts are tightened to the torque specified by the manufacturer.... (which holds everything in place).

Normally no lag bolts are used into the roof plywood, or the roof framing, to mount the roof unit.

Mel
'96 Safari

dennis45 · 06-30-2015, 06:48 PM

Quote:

Originally Posted by DougW

Dutch star with rubber membrane over plywood roof. The lag bolt holes (in the plywood) are stripped. These are the bolts used to hold down the heat pump unit and compress the gasket under each unit. It is a ducted system, so I cannot access the mounting holes from inside the coach. They are 1/2" lags, and I really don't want to up to 5/8''. Any thoughts on how to deal with this would be appreciated. Thank you, Doug

Bummer, I know what you mean about access. I (touch wood) have not had to remove mine but have you thought about using some thing like filling the holes with sticks of hardwood and expoxy? Just an idea... Good luck, let us know how you make out.

asuperheat · 06-30-2015, 06:53 PM

I would imagine maybe a bigger diamiter lag or even a expanding nut might work. Maybe 5/16ths expanding nuts and the right length bolts?

TQ60 · 06-30-2015, 07:53 PM

Visit a well stocked (brain stock) hardware store and see what they have.

You could just epoxy an oak dowel in the hole or drill it a few sizes larger and epoxy OAK dowels into the holes.

Do make a template so you can re drill the holes and use the PROPER lag screw and drill size.

Or look for a threaded insert which would be A round chunk of material threaded in the middle and rough on the outside to allow epoxy.

If you are handy you can make them by buying small pipe like 1/8 to 3/8 size then drilling the inside to correct size to tap threads for mounting bolts.

Then epoxy these in place.

To help get some fender washer which are very large for hole size and drill a few 3/16 holes around the outside then place these over your inserts with a bolt in place and secure with wood screws or stainless drywall screws then epoxy them in place.

DougW · 06-30-2015, 08:17 PM

Mel,
Thanks for your response. It is a 2001 39' Dutch Star DP. It is a ducted ceiling, so no visible framework inside for mounting the heat pump units.

DougW · 06-30-2015, 08:22 PM

Dennis, Carol,
Good thought and thanks. I will look into the idea. Have also thought about fly bolts.
Doug

Ray,IN · 07-01-2015, 07:37 PM

Hollow-wall anchors! When I don't know how deep the screw can go before hitting something, I use a short screw to pull the anchor tight in the hole, then use the included screw to fasten the object to the wall. Sometimes I've measured, then cut the included screw shorter when there is very limited depth behind the wall.

shaman52 · 07-02-2015, 07:01 AM

Doug,

Replaced 3X Penguin's on my Mountain Aire last Winter. Do not re-use the old lag bolts, buy new ones. reason is that the threads get very worn with time. Did you notice that three of the four lag bolts are the same length, with one longer? I had one right front bolt that also did not tighten up even with the new lag bolt. I pondered awhile and decided to try installing a 1/2" or so longer one. The bit longer one held and caused no problems. Make sure that the aluminum tape connecting plenum to ducts is in good shape to prevent air leaks.

Good Luck!

DougW · 07-02-2015, 08:34 AM

Shaman,
Thank you. I had read your write-up about changing all three; good job! I had not considered going longer, only bigger.

DougW · 07-02-2015, 08:37 AM

Ray,
Thank you. Can the hollow wall anchors be used in the existing 1/2" holes?

Ray,IN · 07-03-2015, 10:02 AM

Quote:

Originally Posted by DougW

Ray,
Thank you. Can the hollow wall anchors be used in the existing 1/2" holes?

You'll have to visit a hardware store and inspect them. I think a 1/2" hole accepts a hollow-wall anchor for a 5/16" bolt, which would have similar holding power of a 1/2 lag screw into plywood.
Keep in mind the 4 hold-down bolts for a through-the-roof fastening hold-down are only 1/4".