Vapor Barriers and Drainage for Hollywood Buildings

Two kinds of old Hollywood house, two different floor problems

Walk through the older parts of Hollywood and you see two common building types. The first is the mid-century ranch, often block construction with a flat or low-pitched roof and a terrazzo or tile floor laid on a concrete slab. The second is the older frame bungalow, such as the ones found around the lakes and the original grid streets, which may sit up on short piers or low walls with a gap between the ground and the floor.

The distinction matters because moisture behaves differently in each. A terrazzo floor on a slab has no space beneath it. If a ranch house feels damp, smells musty, or has floor tile that pops loose, the moisture is coming up through the slab or in through the walls and roof, not collecting in a crawl space. A raised bungalow is the opposite. The wood floor can be fine on top while the area underneath holds damp air, wet soil and sometimes standing water.

So the first job on any phone call is sorting out which house you have. Look for low louvered vents, an access panel, or a hatch in a closet. Feel the floor in the morning: terrazzo stays cold and hard, wood floors flex slightly. If you are still unsure, a technician can usually work it out by asking about the age, the floor finish and the foundation. This page speaks to the raised houses and also explains what to do when the answer is that you have a slab.

What a vapor barrier is and what it is not

A vapor barrier on the ground of a crawl space is a heavy sheet of plastic, laid over the soil and sealed to the walls and piers. Its purpose is to stop water vapor from rising out of the ground into the air under your floor. In Hollywood, where the soil is sandy and the water table sits close to the surface, that vapor can be steady in the rainy season and still noticeable in the dry months.

A barrier is not waterproofing. It does not hold back water that runs onto it, and it does not repair a leaking pipe or a rotted joist. It also does nothing about the humid outdoor air that enters through foundation vents. What it does well is cut one specific moisture source, and in many raised homes that is a large one.

Good installation matters as much as the material. The sheet should be wide enough to cover the entire floor of the space, overlap its seams by a generous margin and be sealed there, run up the foundation walls, and be fastened around piers and posts. Cutting around pipes needs care. If the barrier is not sealed, moisture finds the gaps. A thin, loosely laid sheet will tear the first time someone crawls over it, and then it is not doing its job.

Drainage comes first, because a barrier cannot hold back a pond

A lot of crawl space trouble in older Hollywood neighborhoods begins with where the water goes outside. Many lots are low and flat. A roofline without gutters sends all its runoff straight to the soil next to the wall. Landscaping that was built up over decades may have raised the grade beside the house so it now slopes toward the foundation instead of away.

Walk the outside of your property after a hard rain and watch. Does water pool by the foundation? Do downspouts end at the wall? Is a sprinkler head spraying the side of the house? Does the air conditioner condensate line drain beneath the building? Each of these can put liquid into the space you are trying to dry out.

Correcting drainage can be simple. Extending downspouts, regrading a few feet of soil, adding gutters, and moving a condensate line to the yard are common steps. In low spots, a French drain or a small pump may come up in conversation, and a technician can say whether it fits your lot. Be cautious about any plan that puts plastic over a wet crawl space without addressing why it is wet. That is the type of repair that looks good for a season and then smells again.

Minimal original insulation: what that means below and above

Many Hollywood homes from the middle of the last century were built with very little insulation. A ranch house may have a thin layer on the attic floor, none in the block walls, and a roof deck that is simply a roof. A raised bungalow often had none below the floor at all, because the builders did not expect air conditioning to become the main way of living.

That history affects the crawl space discussion in two ways. First, the floor of a raised house was never designed to be the cold surface it becomes under modern air conditioning. The underside of the floor now gets chilled in summer while the space below holds warm, humid air, which is the exact recipe for condensation on the wood. Second, adding insulation in the wrong place can trap that moisture, so the order of work matters.

Many owners find that upgrading the attic is the more effective first step for comfort, because that is where most heat enters. Our pages on attic insulation in Hollywood and on air sealing describe that work. For the floor, a technician will look at whether to leave it uninsulated, use a material that tolerates dampness, or treat the foundation walls instead. The right answer depends on the space.

Flat and low-slope roofs, and why they show up in a floor conversation

It may seem odd to discuss roofs on a crawl space page, but in Hollywood the two are often linked. Flat and low-slope roofs drain slowly, and when they leak, the water can run through the ceiling, down the walls and into the foundation area. A homeowner may chase a musty smell under the floor when the real cause is a roof leak that has been soaking a wall for years.

A technician will ask about roof age, recent leaks, ponding after storms, and any previous patching. They may suggest having a roofer look at the membrane, the drains and the flashing, because fixing the cause is easier than treating the symptoms downstream. This is part of the honest scope of any moisture visit.

The reverse is also true. A damp crawl space can send humid air up into wall cavities and make rooms feel clammy. When both the roof and the foundation are suspect, the order of repairs matters: stop water entering from above, drain the ground below, then seal and insulate. If a contractor jumps directly to the last step, ask why.

Slab homes: what to do when there is no crawl space

If your Hollywood house sits on a slab, an encapsulation service will not help, and a straightforward contractor will tell you that. Moisture in slab homes follows other paths. Humid air can seep through cracks, joints and the edges where the slab meets the walls. Vapor can move up through the concrete if the ground below was wet and there was no barrier under the slab when it was poured.

Signs in slab homes include musty smells in closets, floor tile that lifts or cracks, rugs that feel damp, baseboards stained at the bottom and mildew on the lower parts of walls. These can also come from plumbing leaks inside the slab, a failing roof, or windows that let water in. The sequence of investigation is the same as for any damp building, starting with the source.

For comfort and efficiency in a slab ranch, attention usually goes to the attic, the ducts and the air leaks, not the floor. Our guide to insulating concrete block homes covers the walls, which are the other major piece of a mid-century ranch. If you have uneven temperatures from room to room, the page on uneven room temperatures may help you work out what is happening.

What a technician does under a Hollywood bungalow

Under a raised house the work is cramped and dirty, and a proper visit reflects that. The technician will start outside, walking the foundation and checking vents, grade and downspouts. They will open the access hatch, look in with a light, and measure moisture in the wood and the air.

Common findings in older bungalows include insulation that has fallen from between the joists, stained or darkened wood, rusted nails and hangers, wet or sticky soil, abandoned materials left over from earlier repairs, and ductwork or pipe wrapping that is torn. They also check for signs of termites, such as mud tubes on piers and walls, and for rodents. Where a wood member looks soft or sagging, they will say so and recommend a carpenter or an engineer.

Expect photographs and a clear explanation of what each finding means. Often the result is a short list. Fix the water sources, remove what is ruined, lay a sealed barrier, address the vents according to the rules for your property, and set up a way to check humidity later. Sometimes the finding is that the crawl space is in reasonable shape and a few outside fixes are all that is needed.

Vents, humidity and keeping the space dry afterward

Old foundation vents were meant to dry the space with moving air. In a place like Hollywood, with salty, humid air most of the year, the air that comes in is often wetter than the air inside. For many raised homes, closing the vents and managing humidity inside works better, but it is a decision to make with attention to the building and the local rules, not by default.

If the vents are closed, something must keep the space from becoming a damp, sealed box. Options include a small dehumidifier with a drain line, a supply of conditioned air from the house system, or a simple humidity monitor that tells you when something has changed. Each has costs in power and attention. A dehumidifier must be serviced. A monitor needs someone to read it. Conditioned air can overload a small system if not designed well.

Anything with a flame or an exhaust, such as a gas water heater or a clothes dryer vent, needs a safe air supply and exhaust. Do not seal a space containing combustion equipment unless a qualified person has confirmed how it will vent. If you are not sure what is under your house, ask the technician to identify it before sealing anything.

Three Hollywood scenarios

Examples help, so here are three that come up in older Hollywood neighborhoods. They are illustrations of the thought process, not forecasts for any particular house.

A 1950s block ranch with terrazzo floors. The owner reports a musty smell in the hall closet and a few loose floor tiles near the back door. There is no crawl space. The technician looks at the roof drains, the back wall, the grading and the plumbing, and finds that a downspout empties right against the slab. The fix is outside: redirect the water, check the wall base, and keep the closet ventilated. No barrier is sold because none is needed.

A frame bungalow near the lakes, raised on piers, with wood floors that have started to gap. The owner has noticed a sour smell after storms. Under the floor the technician finds wet soil, fallen insulation, and a condensate line that ends under the house. The plan is to reroute the line, correct the grade at the low corner, remove the ruined insulation, lay a sealed barrier, and talk through vents. A carpenter is recommended for one soft joist.

A small rental duplex with a raised rear unit. The tenant complains of a cold floor and dampness in the bathroom. The landlord assumes it is a crawl space issue, but the access hatch leads to a shallow void with a leaking drain. The first call goes to a plumber. Once the drain is repaired and dry, the space is revisited. This kind of sequencing saves money and arguments.

Getting ready, and how the phone call works

To make the first call useful, write down the age of the house, the floor type, whether you have seen vents or a hatch, and what is bothering you. Mention any roof leaks, flooding in storms, termite history, previous repairs under the house, and whether the home is in a historic or flood zone. Photos of the exterior foundation and any damaged areas help.

Clear a path to the access hatch before the visit and move anything stored near it. Make sure the technician can reach the area without disturbing plantings or locked gates. Tell us about pets and where they stay.

Quotes are given by phone for simple work. A space with unknowns needs an on-site visit, and there is a service call charge that is explained on the phone before anyone is dispatched. We do not list prices on this site because they depend entirely on the space. The general process is laid out on our main crawl space page, and the other work we do in town is on the Hollywood city page. When you are ready to talk about your house, call and tell us what you are seeing.

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