An open lanai or porch is missing one thing: a barrier between the space and the insects, leaves, and weather moving through it. Screening it in does not have to mean new construction, because the structure already has a roof, a slab, and the framing members a screen enclosure needs. What decides the job is whether those existing pieces are close enough to what a screen frame requires, or whether the gaps between them turn a simple screen-in into a repair job first.
Framing and Mesh Across Existing Openings
Screening in an open lanai or porch means building a frame of thin aluminum members across the openings that are currently just air, then splining mesh into that new frame the same way it would go into a purpose-built pool cage. The vertical and horizontal pieces attach to whatever is already there and sound: posts, a low wall, the underside of the roof edge. None of it replaces the roof or the slab. It adds a layer of framing and screen to openings that were never meant to be closed off, which is why the job leans on what the existing structure offers more than a new screen room build does.
Where the space already has a solid overhead cover and a level floor, this remains close to a simple framing-and-screen job, with a door added wherever access makes sense. Where the cover is only a pergola, the slab has settled, or the corner posts are soft, the work in front of a screen crew starts with fixing or adding structure before any mesh goes up. Check whether your HOA or local building office requires approval before committing to the job; that answer depends on your property.
What the Structure Has to Offer the Frame
Before ordering anything, several parts of the existing structure decide how much new framing the job needs and how much is already sound enough to build on:
| Structural element | What it needs to offer |
|---|---|
| Roof or overhead cover | A solid roof or overhang gives new framing an edge to tie into; open sky above the space means the enclosure needs its own roof, screen or solid, framed as part of the job. |
| Slab or deck condition | A level, sound slab gives the bottom track and any solid panel section a stable line to seat against. |
| The attachment surfaces (fascia, beams, posts) | Sound wood or metal at the roofline and the corners is what new framing screws into; a soft or corroded edge gets sistered or replaced first. |
| The opening sizes and door location | Measured openings and a settled spot for the door determine how many bays to frame and where the traffic path runs. |
| Drainage at the slab edge | Water that already runs off the slab edge keeps a new bottom track from sitting in standing water after rain. |
| Kickplate height | Settling this dimension before framing starts is what splits a bay into a solid section below and a screen above, rather than reworking it later. |
A space that offers most of this list stays close to a simple screen-and-door job. A space missing more than one or two items still works as a candidate; it carries a framing or slab repair ahead of the screen work, and that repair is worth scheduling on its own before the screen-in gets ordered.
Before the estimate, run a hose across the slab edge where the new bottom track will sit and watch where water pools; that line is where the track needs a drain gap, or the slab needs dressing.
Choosing the Mesh
The mesh decision for an existing space carries one extra check that a new screen room skips: the framing ties into a fascia and posts that already carry the roof edge, so the installer confirms those members can support the new enclosure before any weave is chosen.
No-see-ums are the reason to weigh a finer mesh on a job like this. Where they are scarce on the property, a standard weave still lets in the breeze and the view, and there is no need to switch.
Doors and Access
Where the door goes is decided as much by the house as by the screen. Access lines up with the existing exit from the house, whether that is a slider, French doors, or a single door, and the screened opening gets framed to meet that spot rather than wherever is easiest to build. Whether that leaf slides or swings depends on the clearance around the opening. Settle the door's exact location and swing direction before the rest of the framing goes in, because moving it later means reframing the opening it sits in.
Screening In vs a Full Screen Room
Screening in an existing lanai and building a new screen room start from different points and land in different places. A screen-in works with a roof, a slab, and existing framing surfaces, adding a frame and mesh across openings that were previously just air. A screen room build starts from scratch: new framing, a full roof system, and can include recessed lighting, outlets, or a ceiling fan in a space meant to function as an indoor-style room.
Which one fits depends on what is standing there now. A porch with a sound roof and a level slab is close enough to a screen-in that building a new room from the ground up would replace structure that does not need replacing. A space with no roof, an unlevel pad, or posts that will not support new framing calls for a larger scope of work for a screen room build, since the missing pieces have to go in either way. The two are less a matter of preference than a read of what the existing structure can and cannot support.
How Install Day Unfolds
Work on an existing space starts with confirming the same points the structure needs to offer: the slab, the attachment surfaces, and the openings get checked against what was measured before the order went in, because framing cut for one set of numbers does not forgive a slab that shifted since the last visit. Furniture, planters, and anything hanging near the openings gets moved clear before framing starts.
New vertical and horizontal members go in first, tied into the sound posts, low walls, or the roof edge, as identified ahead of time.
Fascia and roofline connections sit above eye level, over a slab or a planting bed. Leave that stretch of framing and ladder work at the roof edge to your installer's crew — a slab underneath is an unforgiving surface to land on.
Mesh gets cut to the new bay dimensions and splined into the fresh channel, and the door gets hung and adjusted last, since its swing and latch depend on the framing around it being square and complete. What is left afterward is whatever furniture and planters were moved out of the way to start.
Frequently Asked Questions
How much does a screen frame narrow an existing opening?
By the width of the frame members. The frame members take up their own width on each side of the opening, so a doorway framed for a screen door ends up narrower than the rough opening. Measure the finished opening, not the rough one, before sizing anything that has to pass through it.
Can a lanai with a pitched roof still be screened in?
Yes. A pitched roofline changes how the top track of the frame is cut, since it has to follow the slope at the fascia connection rather than run level as it would under a flat overhang. That step or angle is a framing detail an installer accounts for at the roof edge; it does not rule out screening in a pitched-roof space.
What happens to an existing porch railing when the space gets screened in?
It can stay. The screen framing is built up from the railing rather than tearing it out and sitting on or behind it, so the mesh starts at rail height instead of the slab.
Does an existing concrete pad need work before it can be screened in?
Sometimes, at the joints. A slab that has heaved or settled along an expansion joint needs that joint leveled before the bottom track will sit flat against it for its full length; a bottom track resting on a ridge or a dip leaves gaps under the track that insects use unless the slab is dressed level or the track is shimmed and sealed. That leveling is a concrete step that comes before any framing goes in, not after.
Can screen mesh go over a pergola instead of a solid roof?
It can, with a screen roof framed over or under the slats. Mesh stops insects but not rain or falling debris, so the space stays open to weather overhead unless a solid roof section goes in instead.
Can only part of an open lanai be screened in?
It can. The frame can close off just the bays you choose, with a new wall of framing and mesh running across the slab where the screened section ends. That dividing wall needs what the outer bays need: a sound, level stretch of slab under its bottom track and a solid tie at the roof edge above it. The door into the screened section can go in that new wall, with its location settled before the rest of the framing is cut.
Ask for a screen-in walk-through of your open lanai — the visit confirms whether your fascia, slab, and openings can carry a new frame, mesh, and door. Lanai Guy serves Brandon, Riverview, and the greater Tampa area. Call (813) 316-5971.
